Defense Evaluation - Eddie Rosario

The 2019 Minnesota Twins were an exceptional team. However, they were exceptional despite their defense, not because of it. Starting pitching is receiving the bulk of the worry this offseason, but should the state of the team's defense get the same treatment?

The Twins were 21st among MLB teams in Defensive Runs Above Average (Def) in 2019, with a total of -9.1. That's the lowest among all playoff teams (the Dodgers were the closest, ranking 19th with -5.0 Def). FanGraphs considers the -9.1 Def to be in between Below Average and Poor, sadly placing closely to a Poor ranking.

Other metrics weren't as kind, either. The Twins placed 20th with a -1.1 UZR/150, and 19th with a -7 DRS (Defensive Runs Saved). You get the picture that the Twins were in the lower third oft teams when it comes to aggregate defensive ability.

In this series, I'll evaluate a few of the positions where the Twins could stand to improve defensively. I'll begin with the largest culprit of negative defensive value, Eddie Rosario.

LF - Eddie Rosario (-11.1 Def, -6 DRS, -7.5 UZR/150, -17 OOA)

Rosario was clearly troubled in LF last year, according to most defensive metrics and the basic eye test. How much of this was due to his mid-season ankle injury? That's hard to say. It almost certainty didn't help matters, and neither did age.

Rosario has lost 1.4 feet per second since 2015, according to Statcast Spring Speed. Most of that drop-off occurred in between 2018 and 2019.

Sprint speed clearly effects defense, but how so? Statcast has another metric of "Outfielder Jump". Rosario ranked in the 13th percentile of Outfielder Jump, and the reasons are probably due in part to being... slower.

Components of Outfielder jump including reaction, burst and route. Rosario showed significant decreases in reaction and burst from 2018 to 2019, mirroring the trend in his sprint speed.

Add that together, and Statcast harshly rates Rosario in Outs Above Average (OAA). He had a positive OAA of 4 in 2016, but ranked 225th in MLB with a -17 OAA last season. FanGraphs and Statcast are lined up in evaluating Rosario as a lower-tier defensive outfielder. FanGraphs ranked Rosario as the 3rd worst LF in Def last season, ahead of Domingo Santana and Shin-Soo Choo.

FanGraphs does seems to value one area of Rosario's defense that matches up with the eye test. Dude has a cannon. Rosario is tied with Kyle Schwarber with a 5 rARM (Outfield Arms Runs Saved). Arm strength typically isn't effected by ankle injuries, and doesn't age as poorly as sprint speed.

Aside from the arm, are there any reasons to be optimistic about Rosario's defense? Rosario's impact to the Twins outfield defense can be lessened with a healthy Buxton and Kepler, both of whom rank among the best defenders at their respective positions. However, there's a huge emphasis on a healthy Buxton and Kepler. Without outstanding partners in the OF, Rosario's defense becomes more a liability.

When neither outfielder was healthy in September, Baldelli began to start Rosario in RF. Rosario made 10 September appearances in RF, and accumulated 89 innings at the position throughout 2019. FanGraphs was kinder to Rosario's play in RF, although it was a much smaller sample size than his time in LF. Below are how his stats compared between the two corner positions:

LF: 1048 Inn, -11.1 Def, -6 DRS, -7.5 UZR/150

RF: 89 Inn, 0.2 Def, -1 DRS, 13.5 UZR/150

Perhaps the sample of Rosario in RF was too small and the defensive metrics would have regressed with time. Maybe, just maybe, Rocco Baldelli was onto something. I suppose we'll find out if mixing Rosario into RF was experimentation, or the start of a new defensive alignment even when every starting outfielder is healthy.