Nova returns to the hill, but will his slider come with him?

The Yankees will square off against the Royals in the rubber game of their three-game series tonight.  Toeing the slab for New York will be Ivan Nova, who is coming off the best start of his career (one run in 7 1/3 innings).  Nova's been pitching better recently after a rough start, but he's still only struck out as many as he's walked or hit.  Interestingly, he's completely ditched his slider over his past three starts after relying on it over his first three:

(click to enlarge)

Nova attributed his Spring Training success to the new slider, so it seems strange that he'd stop using it so soon.  It didn't look like a terrible pitch when he used it - of the 26 he threw this year, 15 were thrown for balls, three were called strikes, six were swung on and missed, and two were hit into play.  That's a lot of pitches out of the zone, so maybe Nova feels that using the slider too much prohibits him from pounding the strikezone?  I can only speculate.  Nova currently has the 7th lowest whiff rate among starters, so bringing back the slider, especially on 0-2 and 1-2 counts, might be good for him.