Johnny Cueto has established himself as a staff ace. You can look at his declining ERAs if you’d like — 4.81, 4.41, 3.64, 2.31, 2.78 — but that gives the impression that either Cueto was worse last year than 2011 or, at best, had plateaued.Take a look at his FIPs and you’ll see Cueto has improved every year, even last year — 4.90, 4.69, 3.97, 3.45, 3.27. Last year Cueto jumped his strikeout rate to over 7.00 K/9 after it had resided in the low-t0-mid 6.00s (and declining) for the prior three seasons, and his walk rate fell to just 2.03 BB/9.What’s been the difference for Cueto over the last two years? He’s gone from an almost perfect ground ball/fly ball split to very ground ball heavy, he’s induced a greater percentage of swings on balls outside the strike zone, and he’s cut back on his slider usage in favor of more two-seamers (in 2011) or change-ups (in 2012). Seeing as the change-up is generally a better strikeout pitch than a two-seamer (better for inducing grounders), it shouldn’t be surprising that Cueto’s K rate rose in 2012 and he posted his best ground ball rate in 2011.I love when these things tie together!At a GlanceStrengths: W, L, ERA, IP, QSNeutral: K, K/9, WHIPWeaknesses: nonePlayer ComparisonsBest-case scenario: Matt Cain (SF)Likely scenario: Jordan Zimmermann (WAS), Mat Latos (CIN), Hiroki Kuroda (NYY)Worst-case scenario: Jeremy Hellickson (TB)Johnny Cueto 2013 Fantasy ProjectionThe only thing left for Cueto to prove (in my mind at least) is that he can continue to post ERAs noticeably lower than his FIPs. Matt Cain won me over after three straight seasons of such success, and Cueto has the opportunity to do that this year (Jeremy Hellickson is in that same boat, too). Just because we project Cueto for a 3.10 ERA after two straight years well under that mark doesn’t mean we don’t believe in him. It just means there’s always a luck component to where batted balls go.Speaking of batted balls, this is probably a great time to mention Cueto’s HR/FB rate in a very hitter-friendly park (5.8% in 2011, 7.9% in 2012) is unusually low. I considered that maybe he’s allowing lazy fly balls — which could still be the case — but his league-average infield fly rates don’t seem to back that up. I’d imagine a pitcher allowing lazy flies would also induce a lot of infield flies, but that hasn’t been the case with Cueto.I think Cincinnati will be a very good team this year, though. Their rotation is deceptively good, their bullpen is elite, and adding Shin-Soo Choo to a lineup with a healthy Joey Votto could be devastating. Cueto is durable and will likely go over 200 innings, and the strength of the team behind him could push him over the 17-18 win mark. I don’t draft on wins, but I like to use them as a tie breaker, and Cueto’s win potential in 2013 will help him break a lot of those ties.One last item worth addressing it Cueto’s WHIP. Sorry, folks, but he probably won’t be approaching his 1.09 WHIP from 2011. That year he rode a .249 BABIP all the way under 1.10, and last year it corrected itself back to its usual .290s. Even with a career-best 2.03 BB/9, Cueto allowed too many balls to be put into play to really challenge for a second straight year with a great WHIP. Modest strikeout pitchers have difficulty posting elite WHIPs on a consistent basis, and Cueto is no different. He’s still a great pitcher to own, but his lack of strikeouts prevents him from posting elite numbers across the board.