An alternative to the Maltby MPF rating?

[HSTNGolfer]

I play the 2011 Nike Vr Pro Combo irons with KBS Tour R+ shafts. At the time that I bought them I was also considering the Mizuno MP-63, Titleist AP2 710, TaylorMade MC Forged, Adams CB3 and Ping Anser Forged. I have no particular allegiance to any brand. I recently tested the 2015 Nike Vapor Pro Combo and Vapor Speed irons. There is no doubt in my mind that the newer clubs are more forgiving than the set that I currently use, so I was very surprised when I saw that the 2015 Vapor Pro Combo and Vapor Speed were given MPF ratings of 119 and 116 respectively, i.e. Player Classic. The Vapor Speed is definitely a game improvement club.

 

Ralph Maltby has done excellent work compiling all the measurements that go into his MPF ratings and making them available to all on golfworks.com. I have the utmost respect for him as a club designer and club fitter. However, with the Nike Vapor Pro Combo and Vapor Speed I simply could not agree that the MPF ratings reflect the true characteristics of these irons.

 

I took a look at the description of how the MPF ratings are calculated on Ralph Maltby's site:

http://ralphmaltby.c...etermining-mpf/

It seems to me that the MPF rating is basically calculated by subtracting the vertical center of gravity (COG) value from the "C" dimension plus a few correction factors.

 

I play to a mid single figure handicap and have a keen interest in golf club design. I have read widely on the subject and whenever I get an opportunity I hit as many different golf clubs as I can get my hands on. I have an engineering background and I am curious about why and how the different club heads perform as they do. With all these measurements available I was wondering if I could devise an alternative, hopefully better, numerical system for comparing how forgiving iron heads are relative to each other based on these measurements of moment of inertia (MOI) and COG.

 

I think that most golfers who have an interest in the technical aspects of club design would agree that an iron head with a higher moment of inertia (MOI) should be more forgiving than an iron head with a lower moment of inertia. Also, the longer the blade length, the more forgiving - more room between the center of gravity and the hosel and toe - and a lower and more rearward COG makes it more forgiving by making it easier to get the ball in the air. I do note, however, that Tom Wishon has stated on the topic of "Players forged cavity back vs Muscleback blade" that "This thing of low CG for higher flight is way overblown and rarely works to a visible point."

 

My forgiveness factor (F.F.) starts with the premise that the MOI of the head is the primary determinant of how forgiving an iron is, but then multiplies the MOI by correction factors for the horizontal location of the COG (H.C.F.), vertical location of the COG (V.C.F.) and rearward location of the COG (R.C.F.). The correction factors are calculated relative to the radius of a golf ball (= 1.68"/2 = 0.84"). These correction factors were calculated as follows:

H.C.F. = (HCOG - 0.84)/0.84; HCOG = "C" dimension

R.C.F. = 1 + (RCOG - 0.84)/0.84;

V.C.F. = 0.5x[1 - (VCOG - 0.84)/0.84]

C.F. = (H.C.F.)x(R.C.F.)x(V.C.F.)

F.F. = (MOI)x(C.F.)

 

These correction factors penalize an iron head that has a shorter blade length, higher and more forward COG.

 

The attached table shows how a wide variety of iron heads would compare using this "Forgiveness Factor". I assigned F.F. < 1.75 as a "players iron", between 1.75 and 3 as game improvement and > 3 as super game improvement. Measurements were taken from the manufacturers MPF ratings on golfworks,com.

 

The Nike Vapor Speed (2.44) using this new metric comes out as a game improvement iron with the high vertical COG detracting from the very high MOI. The truly max game improvement irons like the Mizuno JPX EZ (6.28), Ping Gmax (5.61) and Callaway Big Bertha (4.40) are ranked where I believe many golfers would place them based on experience of hitting them. The new Nike Vapor Pro Combo (1.40) scores a more forgiving rating vs the old Vr Pro Combo (1.16), but still firmly in the player's category. The traditional blade irons, e.g. Mizuno MP-5, TaylorMade MB, Titleist MB, Callaway Apex MB and Nike Vapor Pro, all rank as the least forgiving using this metric.

 

Interestingly, most of the Maltby iron heads rank in the super game improvement category with this new metric as would be expected based on their long blade lengths and low and rearward COG locations.

Note that when comparing the latest irons from most manufacturers vs say 2010 models, the "vanishing loft disease" is all too prevalent. We only hit the newer 6 irons further than those from our previous sets because of the lower lofts.

 

I would like to hear from others in this community if they have a better idea of how to rank the forgiveness of iron heads based on the measured design parameters. Perhaps 1 number is just not sufficient to properly rank every kind of iron head.

 

Edits:

Increased font size to make it more readable.

Added MPF ratings for side by side comparison

- color scheme for MPF is: Red < 450, 450 < Yellow < 700, Green > 700.

- color scheme for F.F. is: Red < 1.75, 1.75 < Yellow < 3, Green > 3

 

Observations based on side-by-side comparison:

- Mostly MPF and F.F. agree in the assignments to Player's, Game Improvement and Super Game Improvement.

- Some very high MOI iron heads, e.g. Adams Idea Tech a40S, Wilson D200, move from Player's Classic to Super Game Improvement with F.F.

- Nike Vapor Speed, Wishon 870 Ti and Wilson D100 ES get more forgiving ratings with F.F.

- Player's cavity backs, e.g. Mizuno JPX 825 Pro, JPX 850 Forged and TaylorMade RSi 2 get more forgiving ratings with F.F. - Most other differences occur with irons ranked near the category boundaries.

- The Callaway Apex data looks incorrect. The Apex is a much more forgiving club than both the ratings show.

 

[BrianL99]

http://www.golfwrx.com/forums/topic/1100225-ping-g-irons-and-maltby-playability-factor/

http://www.golfwrx.com/forums/topic/354325-maltby-playability-factor/

http://www.golfwrx.com/forums/topic/107150-maltby-mpf-valid-or-not/

http://www.golfwrx.com/forums/topic/115909-maltby-playability-factor/

http://www.golfwrx.com/forums/topic/1054971-i-dont-know-how-you-feel-about-maltby-playability-factor-but-here-are-2014-additions/

http://www.golfwrx.com/forums/topic/131779-maltby-playability-factor/

http://www.golfwrx.com/forums/topic/121015-is-the-mpf-any-help/

[NoTalentLefty]

Personal failure.

[HSTNGolfer]

Thank you BrianL99. The Wishon article "Technical Comments on the MPF" is interesting and shows the shortcomings of the MPF calculations.

My attachment also seems to have been compressed too much during the upload and is unreadable online. I will try to find a way to ensure that the attached picture can be read.

[Kevmonton]

[quote name='HSTNGolfer' timestamp='1441500820' post='12269820']
Thank you BrianL99. The Wishon article "Technical Comments on the MPF" is interesting and shows the shortcomings of the MPF calculations.

My attachment also seems to have been compressed too much during the upload and is unreadable online. I will try to find a way to ensure that the attached picture can be read.
[/quote]please do, interested

[KYMAR]

I dont like my irons MPF rating, therefore, ill change it. Hey look my irons are awesome now!

[pmcuk]

I haven't read all this in detail - font was very small. But I'm assuming you are using all of Maltby's measurements and substituting something else for the MPF calculation. As far as I can see the relative rankings are more similar than different.

But my problem with Maltby is that it looks like he changed how he measured the VCOG over time. I just can't believe that the S58 scores 0.67 and the S55 scores 0.81. They just don't look that different. There are a load of irons that measure 0.6 something in older models and a load that now measure 0.8 something.

Can anybody explain that one?

[BrianL99]

[quote name='pmcuk' timestamp='1441528573' post='12270986']
I haven't read all this in detail - font was very small. But I'm assuming you are using all of Maltby's measurements and substituting something else for the MPF calculation. As far as I can see the relative rankings are more similar than different.

But my problem with Maltby is that it looks like he changed how he measured the VCOG over time. I just can't believe that the S58 scores 0.67 and the S55 scores 0.81. They just don't look that different. There are a load of irons that measure 0.6 something in older models and a load that now measure 0.8 something.

Can anybody explain that one?
[/quote]


New Math

[VA_Astra]

So the i25's are less playable than the S55's?

[cxx]

If you look at the Hireko/Dynacraft DFSI shaft rating methods you'll find that it takes a tremendous effort to fit a feel to measurable parameters. Not sure it would be doable or worth the effort if it were to revise the MPF ratings formula. I don't think you could do something meaningful without doing a lot of actual testing.

[HackerD]

Nice try OP -- but your correction factors seem a little arbitrary. I have kept a spreadsheet of MPF values and data for irons I've tracked over the years -- about 65 models. Tried your calculation to assess impact. The VCFs are all quite similar, so VCOG has little influence on your overall ratings. That's where there's the biggest divergence from MPF, which gives more weight to VCOG. But maybe that's your point, that VCOG has too much influence on MPF?

I've actually played 9 of the 65 models I've tracked. The relative rankings among those 9 are not too different in the two ways of calculating overall forgiveness. So not much I can conclude there. Of course neither system measures turf interaction, which for me is an important factor.

Also I agree there seems to be a question of stability of Maltby's measurements over the many years he's done this. All the high values of VCOG have been the last couple of years it seems.

[Nessism]

I didn't go through all the calculations. Font is too small and it hurts my eyes. At any rate, my feeling is that the MOI already takes C dimension into consideration so I'd drop HCOG out of the equation.

[highergr0und]

Why do these ratings need to exist? Just go hit irons and decide what you like the good old fashioned way.

[Awalkspoiled]

I lost patience with the math, so I just went through OP’s list, looking only at the irons I myself had hit enough to judge. Those were the Matlby TE, AP1 712, Wishon 870ti, TM Rocketbladez Tour, AP2 714, MP H5, 825 Pro, Cobra AMP Forged, Wishon 555, Ping S56, Hogan Apex, Miura PP9003.

I listed them in descending order of ease of play for me, and that’s pretty much the order OP would have them also, except for the Mizunos, maybe, so whatever he did it seems to me to be pretty accurate, at least for my game! FWIW I’m gaming the Rocketbladez Tour on custom Program shafts at the moment, but if I got to pick from that list my favorites would be the AP2 714 or the MP H5. The Maltby TE I’ve played for many years in the past and would be happy to play them again. Nothing would induce me to hit the Miuras again ever.

[pmcuk]

[quote name='Awalkspoiled' timestamp='1441551452' post='12271638']

Nothing would induce me to hit the Miuras again ever.

[/quote]

You'll make a lot of buddies on this site.....

[borker]

Being a numbers nerd myself, I have been drawn to the possiblity of a quick way to methodically determine the "forgiveness" of an iron. MPF definitely catored to this and I have been looking at it ever since I discovered it years ago. But it has been a conflict of mine because I WANT to believe it, but real-life testing just doesn't always agree with it so I can't count on it, despite me constantly checking it.

MPF also weighs on me when I know an irons particular rating in my mind. Your example above hit home with me because it was literally an EXACT situation I had come across just a week ago myself. I had VR Pro Combo irons that I loved the feel and look plus felt they were actually pretty forgiving as opposed to the poor MPF they had scored. Some days I felt I would keep them forever, but on off striking days it constantly would weigh on me just maybe I am making the game harder than it should and the MPF was right. I sold my VR Pro Combos and this poor MPF was sort of part of reason why.

Then a few days after I sold them I happened upon a lightly used set of the 2015 Vapor Pro Combo's at local golf store. I knew these things were MPF rated at just about LESS forgiving than even some old fashioned blades and curiously jumped into simulator to try these "demanding" things out. Now I know it is indoors and hitting off a mat, but as you discovered, I felt these 2015's were much more forgiving that the MPF gave them, as well as even more foregiving than the 2011 VR Pro Combo's I just had in my possession. Draw after draw and nice dispersion. The head looked big and inspired confidence as well. Had I had the money I might have bought them. But maybe out in real golf world (on grass and where a shot counts) MPF would end up being right? I don't know.

I have also over the many years, being an iron ho, gone through owning 12 sets and hit a wide variety more whenever I wander into a golf store. The Titleist 695MB's I had for 6 months were definitely not as forgiving as MPF rates them imo (MPF of 512, better than most any other MB) and I would put them harder to hit for SURE than the 2011 VR Pro Combo's I had. Some, like the Eye 2, I would rate even slightly higher than MPF has them. Ping S59 slightly less.

I think the problem with MPF, as Wishon brought up before, is that his concept and ratings were never tested on live golfers in some sort of blind testing (difficult, I know). So the rating is a concept of what forgiveness is determined by a expert clubbuilder and then assigning a measure to those parameters and then creating a formula that combines those measures in another deterministic way to get a final rating. Sort of like rating an NFL team based only on what one determines are winning factors and including them into a formula rather than just using the wins column (in which many ratings attempts, like Sagarin, do). As someone above mentioned to just go hit the irons. But with so many to choose from, it is impossible to hit them all.

I actually have come to think the shaft is also a factor to weigh in on an irons forgiveness. The shaft and head work together and haven't ever been thought of as a whole when people talk of an iron's forgiveness. Even the same shaft you pulled from a set you love and put into another head could be influenced and feel/react different in another head due to the COG and rotation forces the head my impart. I think this because I have messed with this.

I also wonder if maybe some pro's are giving up strokes over a weekend due to poor MPF irons? They may not believe it or feel they gain them back in other ways (like having more ability to control trajectory), but still wonder. Tiger switched to his lowest MPF rated iron of his career for 2015, how'd this year go?

[PowderedToastMan]

[quote name='borker' timestamp='1442825465' post='12342870']

I also wonder if maybe some pro's are giving up strokes over a weekend due to poor MPF irons? They may not believe it or feel they gain them back in other ways (like having more ability to control trajectory), but still wonder. Tiger switched to his lowest MPF rated iron of his career for 2015, how'd this year go?
[/quote]
Correlation does not equal causation.