When Nova returned from a minor league stint in the middle of 2011, he started 11 more games for the Yankees in July, August, and September. Nova may have been the best Yankee starter for the second-half of 2011, as he emerged with a new devastating slider and a 3.18 ERA in 73.2 innings. We expected a lot out of Nova in 2012, and we received some of that, but only in doses. In June and July, Nova pitched 7 games and 47.2 innings with a 1.70 ERA, allowing just 40 hits and earning 42 strikeouts. In the 11 games following that, Nova pitched to a 7.05 ERA, while batters were hitting .309/.372/.539 off of him. Even at 26 years old, it's hard to tell what kind of pitcher Nova will become. His slider and curveball were extremely effective pitches, even in 2012. The curveball accounted for a 13% whiff rate and batters only hit 11 line drives off the 741 pitches all season. The slider had a tremendous 23% whiff rate, though batters were able to hit the pitch around. His curveball and slider combination is still something that could make him a top of the rotation pitcher, however he hasn't shown any overall consistency.
While the slider is his strongest strikeout pitch, he does seem reluctant to throw it, and in 2012 he only threw it 13% of the time. His slider is still relatively new, and it's no surprise that he's still modest about using it. At times, Nova seemed to lose control of the slider, and according to PITCHf/x, the movement on the pitch can change dramatically. The right-hander is still learning how to and when to throw the breaking ball, but facing major league hitters in Yankee Stadium isn't the easiest platform.
Outside of his slider and curveball, his four-seam fastball gave him the most trouble last season. Of the 3410 fastballs he threw, hitters only whiffed on them 136 times. In comparison, batters hit 166 line drives off of the pitch, and in total they batted .372 with a .243 ISO. In terms of velocity and movement, the fastball averaged 93.5 mph, and horizontally it moved more than 5 inches into right handed hitters with 7 inches of rising action. Compared to most four-seam's, the pitch reduced rising action in favor of horizontal action, and the result was nearly double the amount of groundballs compared to flyballs.
But I don't believe the four-seam fastball is a bad pitch, the trouble is more likely with how he used it. When behind in the count, Nova threw the four-seam fastball more than 75% of the time. In comparison, CC Sabathia only threw his four-seam 41% of the time, and his sinker 13% of the time. Going by month, Nova started to throw fewer and fewer fastballs in these situations as the year continued, especially when his troubles began in July. One has to wonder if part of his troubles were caused by teams catching on to his fastball heavy approach.
In terms of overall statistics, Nova also had a major differential between his ERA and FIP. His 4.60 FIP looks like a more accurate summary of the pitcher's 2012, rather than his 5.02 ERA. His 3.92 xFIP also indicates how much the high home run rates affected his performance.
By maintaining his walk rate and increasing his strikeout rate to 20.5%, Nova showed that he has the tools to be a strikeout pitcher with command. His problem is his hittablility, and as he learns to better use his slider, and throw it more consistently, it should become a bigger part of his repertoire. Assuming he can get the slider working with his already strong curveball, he can throw fewer fastballs in hitter-friendly counts, and thus give up fewer home runs and extra base hit.
Sabathia's sliders remains one of the best in the game, and it wouldn't surprise me if the Yankees team them together in workouts. Nova may also find success if he began throwing a two-seam fastball along with his four-seam, like Sabathia did in 2009. By throwing a combination of both fastballs, hitters cannot sit on his four-seam, and the amount of groundballs should increase, thus preventing extra base hits.
Overall, I'd expect Nova's 2013 ERA to come close to his 2012 FIP. It would be a decent improvement for a fifth starter, but as a 26 year old, he can still improve on his slider and fastball selection. If this happens, the sky is high for the righty, and that's why the Yankees favor him over David Phelps and Adam Warren.