What kind of difference would you expect between a lefty with 76 contact, 98 power, 75 vL, 85 vR, 82 eye and a righty with 70/92/70/75/80 in these categories?

Another owner remarked that the two are essentially the same player which surprised me... I expected that the second player would be good, but significantly less productive than the first player?

The definitions of "essentially" and "significantly" play a big role here.

Say the first guy has an OPS of .900.  5% less is .845.    Is that "essentially" or "significant"?

And, yeah, I'd expect a 4-8% difference between the two.

My RC27 prediction formula, without spd/br since you didn't provide it, says 6.7% difference.

The first player has been about 8 rc/27 in this career. So you would expect the other player to be about .5 worse? Speed and fielding are pretty even. It will never happen, but if player A, 27 with 5 yr 30m deal was traded for player B, a rookie (seems to be done developing), who do you think would "win" the deal?

They are essentially the same... as long as you play in a very special world where all pitchers are left-handed.  In any normal HBD world they're not the same.  

My formula comes up with the same basic answer as Mike's does; 7.2% difference.

Posted by groth911 on 7/25/2015 3:27:00 PM (view original):
The first player has been about 8 rc/27 in this career. So you would expect the other player to be about .5 worse? Speed and fielding are pretty even. It will never happen, but if player A, 27 with 5 yr 30m deal was traded for player B, a rookie (seems to be done developing), who do you think would "win" the deal?

The winner would depend on context; this could be a win-win trade.

Edited to remove evidence of my inability to read posts carefully.