Nathan Eovaldi has had a very up and down first season for the Yankees after a somewhat controversial trade brought him to New York along with Domingo German in exchange for Martin Prado and David Phelps going to the Miami Marlins.
The trade was a worthwhile gamble in my mind because Eovaldi has obvious tools and upside to work with and is under team control through 2017, while Prado is a league average player on the final year of his deal. Prado wasn't going to make or break the Yankees this year, and they needed the arm. He's been less than league average for the Marlins this season with a 88 wRC+.
Eovaldi hasn't showed much improvement thus far with his strikeout rate or the amount of hard hit balls he has given up this year. He has an inflated 4.81 ERA, but without the 8 runs he allowed in less than an inning on June 16 in Miami it would be under four. Eovaldi's 3.78 FIP and 3.84 xFIP show a better story. His .354 BABIP and 10.3 percent HR/FB rate are both well above his career averages, and his line drive rate and hard hit percentage are about right in line with his career average, so he has had some poor luck on his side.
The disaster in Miami has also clouded the fact that Eovaldi has gotten better results recently. He has pitched a quality start in four of his last seven starts (none have been the six inning, three runs allowed "quality start"). There was another start on June 5th against the Angels when he pitched 5 1/3 innings and allowed one run, so you could say that five of Eovaldi's past seven starts have been good.
The biggest obstacle Eovaldi faces is getting out lefties because he is a completely different pitcher against them than he is against righties. Right-handed batters have a .289 wOBA against Eovaldi, while left-handed batters have a .412 wOBA. Basically, Eovaldi is an all-star pitcher against righties and a Triple-A pitcher against lefties. This might explain his solid last two outings against Detroit and Houston, since those are such right-handed dominant lineups.
Developing secondary pitches was the key for Eovaldi to improve this season to go along with his blazing fastball. Unsurprisingly, Eovaldi's offspeed and breaking pitches have been successful against righties and poor against lefties. Righties are hitting .277 against his slider, .167 against his curve and .103 against his split. Lefties are hitting .342 against the slider, .385 against the curve and .261 against the split. Also, lefties are killing Eovaldi's fastball with a .408 batting average and a .592 slugging percentage.
The split has been the pitch Eovaldi has added to his repertoire this season, and it has been far more effective than his slider or curve. However, even that has a big platoon difference with righties whiffing 21 percent of the time and lefties 12 percent. With his secondary pitches being ineffective, hitters can just sit and wait on that big fastball. It seems like Eovaldi would really benefit from trying to develop some kind of two-seamer or cutter that he can get in on lefties. He can really do away with one of the curve or slider.
The Angels are another right-handed dominant lineup, so that is another good matchup for Eovaldi and something to keep in mind if he throws another solid outing. However, until he can figure out how to get lefties out Eovaldi will never fulfill his potential.