It could very well just be just a matter of physical comfort,or it could be the player just adjusted to what they had when they got done jacking the shaft off for months/years with a green Scotch-Brite pad or a half sheet of 400 sandpaper,believe me I've seen it and way worse.
I met a guy at a tournament in Kennett,Mo that bought a pretty nice for the time piloted steel jointed McDermott one time that ordered the shafts at 11.5 mm with a 14" straight taper. He did well with it,but I hit maybe 30 balls with it after the tournament and I was almost slack-jawed seeing the way it could make the cue ball juke around,but I found that particular trait to be completely uncontrollable for me,even with 18oz weight. He said he started out playing with an old Dufferin 60" snooker cue that he sanded himself to fit his VERY small hands and short,Jackie Gleason type fingers.
I also knew a guy from over that way that started out with a standard 13.25 Meucci that wound up about like that McD,after he sanded on it with the Scotch-Brite,which was always fresh,and followed that up with 0000 steel wool. I could feel what had to be a .020/.5mm hourglass taper back to about 10" from the ferrule. When he broke with it,if he was to ever hit a rack like Shane that shaft would have went thru the back of his hand when it broke,let alone me or Mike Sigel.
My Schon was ordered with standard taper 13.5 shafts and ivory ferrules. I still play with those shafts,but they now feel like a brand new Predator Z2 does taper-wise,and pretty close at about 11.5mm.
They still feel as good as they always have,esp since over the course of 20 years of serious but never full-time play,I now have a buildup of scar tissue or something in the 2nd joint of my bridge hand index finger that is just more comfortable in some cases. The Schon I break with felt WAY too big at a perfect 13mm,and I now prefer a gradual growth the whole way back,much like a SW or modified pro taper,and right at 12.75 is perfect these days. The non-original shaft I've been playing with lately feels to me the same as a brand-new unsanded Predator 314-2,not the Z,and it's like .002 over that. It's also 31",but the feel I describe is in the front section.
Part of this is also because I have more or less forced to play on flat-out dirty,and always slow cloth at times,I'd have to adjust maybe to play consistently on faster tables,like the oversize 8' Valley bar box 3 blocks from my house,that is freakishly fast at times even with cruddy,cheap balls,but rolls off so bad I wouldn't bet over 20 a game on it unless I was 90% supposed to win.
That's pool in NW Tennessee at the moment,until I can do something about it,LOL. Tommy D.