Last season was a rough one for the Diamondbacks for many reasons. One of the saving graces of a lost season is supposed to be the ability to give developing talent a strong evaluation to determine just what the team has in the pipeline. Somewhat painfully for the Diamondbacks, even this was denied to them when it came to evaluating tonight's starting pitcher, Rubby De La Rosa.
At first blush, this may seem silly. De La Rosa led the team in innings pitched in 2015, throwing 188.2 innings over 32 starts. De La Rosa also led the team with 14 wins. At times, De La Rosa was dominant, showing off the tools that had long had him listed among the better starting pitcher prospects in the game. Other times he clearly demonstrated the issues that prevented him from ever taking that last step forward, leaving him a poster child for things that "could have been". In short, De La Rosa was good just enough to continue intriguing the Arizona front office, but was still inconsistent enough that after a full season, the team still did not know what it had in the hard-throwing right-hander.
De La Rosa's troubles really boil down to one particular issue, and it is a glaring one. While he was dominant against right-handed hitting in 2015, he was atrocious against left-handed hitting. The difference was night and day. With a .214/.265/.611 line against right-handers, it is stunning to see that his line against left-handers was .315/.382/.949. Those are Miguel Cabrera/Paul Goldschmidt numbers against him by left-handed hitting. One would think that such a disparity would tell the Diamondbacks all they need to know about Rubby De La Rosa as a starter. Yet despite those gaudy numbers against him from the left side, his overall body of work in 2015 was serviceable for a back-of-the-rotation starter. That, combined with the obvious potential locked away in that powerful right arm of his, earned De La Rosa a very early endorsement from Diamondbacks CBO, Tony LaRussa, as Arizona's #4 starter, pushing left-hander Robbie Ray into the position of having to fight off competition to remain in the rotation.
When a team is flirting with the very real possibility of losing 100 games in a season like the Diamondbacks were in 2015, it is defensible to possibly sacrifice a few wins in order to develop a young talent like De La Rosa. During the offseason though, the Diamondbacks made it very clear that they were in it to win it in 2016. They handed out a record contract to Zack Greinke, stealing an ace from the division rival Los Angeles Dodgers. They traded a significant chunk of their young talent to augment that signing in order to bring over Shelby Miller. The expectations for the 2016 Diamondbacks are high. Anything less than a playoff run is going to feel somewhat disappointing at this point, despite the loss of A.J. Pollock in the final game before the season. With those sorts of expectations, whittling away wins in order to encourage further development is no longer a luxury the team can afford. Enter again, Rubby De La Rosa.
To his credit, De La Rosa spent the offseason working on his pitches in an attempt to address his difficulties against left-handed hitting. The first real challenge came in game four of the season, at home against the Chicago Cubs. The Cubs stacked their starting lineup with six left-handed hitters. De La Rosa threw 70 pitches but only managed to survive 3.1 innings, allowing seven runs (six earned) on six hits and three walks. The outing was short enough, and the bullpen was in enough need of rest that De La Rosa pitched an inning of relief two days later on his side throwing day.
Granted, De La Rosa's start against Chicago was just one outing. However, the Diamondbacks are in the unenviable position of getting off to a very rough start, and are tied with San Diego at the bottom of the NL West standings, three games behind the division leading San Francisco Giants. While divisions are not usually won in April and May, they can be lost there, and while the Diamondbacks have no reason to panic about their season just yet, they do need to be wary of just how many games they let slip away, especially during stretches of already sub-par play.
With De La Rosa's stuff against right-handers, he makes an attractive option out of the bullpen to shut down the opposition's powerful right-handed bats late in games. Given that most starters moving to the bullpen enjoy a slight velocity bump, this could turn De La Rosa's already electric fastball into a 97-98 mph screamer. The organization has a number of arms either ready or nearly ready to step in and take over De La Rosa's role in the rotation, including Tyler Wagner and Zack Godley. Tonight, De La Rosa takes the mound for his second start of the season against the worrisome division rival, Los Angeles Dodgers. The Dodgers have some left-handed hitting of their own, including first baseman Adrian Gonzalez. Should De La Rosa struggle again tonight, will the Diamondbacks pull the plug on the Rubby De La Rosa experiment? Will he have finally come to the end of his leash as a starting pitcher? Might he be asked to build upon his very strong showing out of the bullpen from four days ago and take on the role of righty specialist? If the team wants to give themselves the best chance to win the division in 2016, just how much longer is the leash for Rubby De La Rosa?