If my eyes don't play tricks on me, i think the majority plays the AP2's. I have the original set from Spring 2008, changed to 710 CB's and now play 712 MB's

I was wondering the same thing this morning, mainly not what the total numbers of clubs are but what the winners use.  Going back on a few blogs for the past year or so, it looks like the AP2's dominate winning.  710, 712, they just seem to be in more winners bags that the MB's or CB's.

You can check what irons every titleist bag player uses here.

http://www.titleist.com/players/Default.aspx

There are a lot of AP2 irons on tour.  You can look under "Players" on Titleist.com but I would bet that AP2 is the most popular.

It's a tie between the cb and mb

From what I have seen AP2 for the headliners like Watney, Zach Johnson etc.  A few blade players like Mcilroy with the MB. And very few still do a combo for AP1 long irons and AP2 short, like Ben Curtis. I would say all of them get a fair amount of play though with the AP2 and the CB the most common as the only iron in the bag.. Very few play the MB and even fewer still play the AP1. They have to keep the MB though because their die hard players wont play anything else. I caddied for an Australian Nationwide player and he played MB. Didn't play well, maybe he should switch to something more forgiving. :-)

Retail wise though, they just don't make as many sets of the MB or CB. By far the AP2 is their most popular tour iron, with CB 2nd, MB, 3rd, and AP1 last, although all are in play on tour.

Retail wise, the AP1 and AP2 are by far the most popular, though most amateurs playing the AP2 should probably be playing the AP1.

Even the AP1 is a decent iron and not really that much of a shovel. If it were a Callaway club it would be a players iron over there.

I really doubt he played poorly because of mb irons. A pro on any tour could play with a toilet plunger. People have a fear of blades. No matter what iron you use a sucky shot is just that.