A case for Ivan Nova

I know the Yankees are in a tough spot with 7 starting pitchers and 5 slots in the rotation. I also know that having that problem is a great problem to have. I won't suggest a 6 man rotation (specially after noticing how it affected CC last year), nor will I pretend to know what is best for the Yankees going forward.

I will simply present you why Ivan Nova should be a lock for this year's rotation.

We all have heard that Ivan Nova overperformed his peripherals last year and, since he doesn't have multiple years doing it, we should expect regression in the wrong direction. Nova indeed overperformed his underliying number to the tune of a pitching triple slash of 3.70 / 4.01 / 4.16 (ERA/FIP/xFIP) that suggests he was lucky stranding runners (ERA<FIP) AND with the long ball (FIP<xFIP).

You may or may not believe in the predictive power of xFIP, or even in the broader concept of DIPs, but what you cannot ignore is that Nova was a different pitcher after he was recalled to the majors the 30th of july.

Now I need to define the average AL starting pitcher this past season:

6 innings per start
K% 17,20
BB% 7,40
GB% 43,90
LD% 19,60
ERA 4,21
FIP 4,08
xFIP 4,04
K/BB 2,33
BABIP .293
HR/FB% 10,00

Before the demotion Nova started 16 games, winning 8 games and losing 3, while having a 4.05 ERA. He pitched 91 innings and averaged a little more than 5 2/3 innings per start, while striking out 12,69% and walking 9,2% of all the batters he faced. His K/BB was an aweful1,42.

In the batted ball department, he posted a league average BABIP (.292) and HR/FB (10,97%). He produced a great number of ground balls (58,36% GB) and allowed a lower (better) than average number of line drives (16,72% LD).

After being called up to start a game against Baltimore (a fine 7 innings pitched, 2 runs, 6 SO and 1 BB performance by the way) he started 11 games and posted the following numbers:

8 wins, 0 loses
6 2/3 innings per start
K% 15,77
BB% 6,71
GB% 49,11
LD% 19,19
ERA 3,18
FIP 3,43
xFIP 3,87
K/BB 2,61
BABIP .290
HR/FB% 5,63

The offended Nova came back striking out more people (24% increase), walking a lot less batters (37% decrease), therefore upping his K/BB from 1,42 up to 2,61 (84% improvement), keep in mind that league average was 2,33. He managed to overcome his below average SO% numbers with improved control.

His BABIP stayed at league average. His GB% declined but stayed above average, his LD% increased but stayed a little better than league average.

Unfortunately here comes the first warning sign: his HR/FB% was a really low 5,63. That's a number we cannot expect him to keep for a whole season, because last year only 3 qualified starters managed to beat that number:
Matt Cain, Roy Halladay and Doug Fister .
Halladay is one of the best (if not the best) pitchers in baseball. Matt Cain and the Giants have been defiling the odds (and DIPs theory) for a while now, he is a different kind of species. I don't know a thing about Doug Fister so lets move on.
I'm almost certain Nova will not post a HR/FB% that low next year, so we should expect that number to regress towards league averague. That's why we have xFIP! xFIP normalizes HR/FB% and it tells us that if Nova continues to pitch like he did after he was called back, he should post something closer to a 3,87 ERA instead of the 3,18 mark he posted.

While xFIP is really good at predicting future performance (only SIERA is better, but its a lot more complicated), FIP tells us more about what happened, and Nova posted a FIP that was 15.93% better than league average.

His season triple slash of 3.70 / 4.01 / 4.16 (ERA/FIP/xFIP) include before Nova and offended Nova, and by only looking at it people believe that Nova will have to get lucky to post a sub 4 ERA. By looking at his "second half" triple slash of 3,18 / 3,43 / 3,87 (ERA/FIP/xFIP) and acknowledging that he made a conscious change in his game, I see a pitcher that is improving, wants to get even better and if it gets lucky, could post a sub 3.30 ERA.

So, yes, I want Ivan Nova in next year's 4th spot.

PD: The narrative was that he gained confidence in his slider and started using it more, becoming a more dominant starter. Next time I will try to confirm if his slider use went up, if it became a more valuable pitch and if he changed his approach in different counts to confirm this theory.

Disclaimer: FIP and xFIP might not match with season splits of Nova because I had to recalculate them. K/BB does not include IBB. Sorry for the format, the pace and the blabbering, first time writting anything for others.