I've certainly found it harder to get batsmen out (not that I bowl all that much - the low frame rate when you've got attacking fields is a tad off-putting), but that's good, really, because I felt it was a little easy before and if you cranked the difficulty up to compensate then batting soon becomes impossible.
I don't really get the whole "the game's messed up because I can't play it very well" argument - either drop the difficulty, or just practice and improve at the game - that's the entire point (especially of career). You can see plenty of videos on Youtube where people play the game very successfully - the key is, they're just better at it. Keep plugging away.
Yes and no. I agree that bowling was too easy and that adjusting the difficulty is a good idea - if the balance is right.
It sounds like the guy was decent enough batting on Pro and maybe wouldn't have minded wickets being a little harder - a subtle adjustment. It does seem that wickets are much, much harder to get on Pro, to the point where batting is now almost easier than the bowling.
If that's the case, dropping this guy down to Amateur will likely not satisfy him at all. The bowling may end up slightly too easy and the batting way too easy.
I feel that bowling would've been better on Pro somewhere between where it was and where it is, which may be a hard adjustment to make.
There also seems to be a lot of contention (and has been tweaks or not) since release between those who feel one way about the difficulty difference between Pro and Veteran and those who feel the other. It must be a hell of a thing for Big Ant to know what specifically to do. Maybe a 6th difficulty between Amateur and Pro called Semi-Pro?
I myself don't find the bowling too hard on Pro, just a little boring now due to the adjustment. It doesn't seem like you can work out a batsman and find out what will get him out, you just try and bowl various good deliveries as much as you can, well at least that's my experience. The frequency of wickets now does make the bowling experience a little too plodding at times.
One thing to take into account though, we are all at various stages of careers, which makes it hard to read how much is a balancing issue and how much is a player development issue.
Shame there wasn't a season mode or such we could create for team play instead of individuals in careers. That'd reveal how the difficulty is playing out with properly developed players, rather than career individuals at various stages of development. Mind you we can do that with tours etc, I suppose.