Contact rating = batting average is correct by our experience and has been pretty much confirmed that the rating is designed to replicate. I'm not sure about Power rating exactly, but it's pretty obvious that what it affects most is the speed of the batted ball... the higher the Power rating, the faster the ball travels off the bat for the most part... for grounders, line drives, fly balls.... all. hahahaha
In regular gameplay, I think Contact is probably most well correlated with line drive % in details.... There has been pretty solid evidence (e.g., sabermetrics) that high batting average is mostly a result of more line drives (which tend to fall between fielders before being caught). So high Contact hitters produce more line drives compared to grounders, fly balls, popups, etc.
I think Power pretty much translates to how much jolt you can put into the batted ball.... it tends to work like that in looking at numbers in simmed games.... but in regular gameplay it feels that it has slightly larger effect than just putting jolt, since by making the batted ball travel faster, high Power hitter can convert some less-quality hits into safe hits, finding holes and landing between fielders. So when you compare high and low Power hitters with same Contact, the former tends to outperform (which makes sense even in real life.....).
I just cited HR / H, because it's the easiest number to calculate (almost all baseball stats sites/books has the number), and so long as you can neglect park factors, hitting approach, swing angle and all, it represents what we conceive as power fairly well....... hahaha.
I don't know this exactly, but HR/H does correlate well with HR numbers in the game:
http://www.operationsports.com/forum...post2042370718
That's from simmed games though.... but I doubt things are that different in regular gameplay for this specific case....... haha.
One thing I'd also add is that I think partly the reason why the game doesn't *have* to give exceptionally high Power ratings to those who hit for high averages but still produce 30/40+ HRs or so as well, is that those types of hitters probably are compensating between power and contact approach to some degree... meaning they choose to hit for very high average by not going for fence all the time (reduced power).