Given the numbers he put up in the AL East, it's frightening to imagine what he is capable of doing now that he's in the NL... What is the likelihood that he posts a sub 2.00 ERA? Sub 1.00 WHIP?
Assuming he remains healthy (please stay healthy Roy), he should log in the neighborhood of 250 to 260 IP. What are reasonable projections? 22 Wins, 220 Ks, 2.10 ERA, 1.05 WHIP? I think those projections are very reachable for Roy - I wouldn't call them conservative, but I also wouldn't say I'm going out on a limb. We're talking about a guy at the top of his game who has consistently put up elite numbers in the least pitcher friendly division in baseball. They say moving from the AL to the NL typically shaves 0.5-1.0 off of a pitcher's ERA - well he didn't just move from the AL, but from the AL East. I think an ERA of 2.45 is his absolute ceiling, with a potential floor around 1.8. I see 1.10 as the ceiling for his WHIP, with a floor of maybe 0.90.
A 24 Win, 230 K, 1.80 ERA, 0.90 WHIP season is possible and might just make him the most valuable commodity in fantasy baseball. Sure, it's more likely that he posts a line similar to the one in the second paragraph, but I fully believe Roy is capable of posting the absurd numbers listed above (not that the more 'conservative' numbers aren't absurd, but, yeah, you know what I mean...).