Red Sox lefty Eduardo Rodriguez working on revamped slider

Boston Red Sox lefty Eduardo Rodriguez has been working on his slider in spring training with the help of Chris Sale and Pedro Martinez.

Eduardo Rodriguez is poised for a big year for the Boston Red Sox. The lefty has shown flashes of brilliance in the past but has yet to put together a full breakout season due to a mixture of health and inconsistency. The former is somewhat out of his control but he arrived in camp in great shape. The latter could be resolved by an improved slider that he’s been working on this spring.

Masslive.com’s Christopher Smith reports that Rodriguez has been developing a new-look slider this spring with the help of Chris Sale and Pedro Martinez. Sale’s trademark slider is one of the filthiest pitches in the game. We last saw him use it to put away Manny Machado on a swinging third strike to clinch the World Series. Martinez is arguably the greatest pitcher in franchise history and baffled opposing hitters with a devastating slider of his own in his heyday. E-Rod couldn’t ask for a better pair of teachers.

Rodriguez showed off his new pitch when he threw a live batting practice session at JetBlue Park on Tuesday. Manager Alex Cora saw a noticeable difference in Rodriguez’ slider and was impressed by how unbelievable the lefty was “stuff-wise.”

"“It was an in-between slider-cutter kind of thing,” Cora said. “But it’s a real slider (now).”"

Rodriguez has always thrown a variation of the slider which, as Cora observed, was actually closer to a cutter. E-Rod threw his slider a career-low 8.3% of the time last season while seeing a significant jump in the usage of a true cut-fastball (19.0%), per Baseball Savant.

The decline in usage of his slider was due to the ineffectiveness of the pitch. Opposing batters destroyed Rodriguez’ slider to the tune of a .400 average, .800 SLG, and .426 WOBA in 2017. The pitch saw slightly better results by relying on it less often last season but it was still easily the worst pitch in his arsenal. He limited opponents to a modest .222 average but the .778 SLG and .425 WOBA showed hitters will still crushing his slider.

Developing a true slider would give Rodriguez another weapon to put away batters with that further differentiates itself from an emerging cutter that has become his best pitch (.212 AVG, .265 SLG, .248 WOBA last season). That would give Rodriguez five reliable pitches in his arsenal, along with his sinker, changeup, and a four-seam fastball that remains his most frequent option.

Spring training provides the perfect opportunity to work on new tricks. Rodriguez has been held back by knee injuries that forced him to rehab in previous offseasons. He seems to have put those knee issues behind him following patellofemoral ligament reconstruction in October 2017 but a gruesome ankle injury cost him significant time in the second half of last season to derail what appeared to be a breakout season.

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Rodriguez finished the year 13-5 with a 3.82 ERA, 1.26 WHIP, and 10.13 K/9. The ankle injury limited him to only 23 starts and he was relegated primarily to bullpen duty following his September return.

This is a rare opportunity for Rodriguez to complete a normal spring training without enduring a rigorous rehab schedule. That affords him more opportunity to work on his craft by tinkering with his slider, potentially turning a weakness into a strength.

"“If it works, I’ll throw it,” Rodriguez said about the new slider. “This is the best time to start working on that pitch. It doesn’t hurt your numbers on the back of the cards. … I’ll throw it in the (spring training) games. And if it works, I’ll put it in, in the (regular) season.”"

He still has a long way to go before determining if this new slider can be relied on during the season but the early returns are promising. We shouldn’t expect Rodriguez to suddenly resemble Sale or vintage Pedro on the mound but it’s reasonable to believe their guidance can help him improve.

The 25-year old aims to make the leap into Cy Young contention where several of his fellow rotation mates have been before. Rick Porcello and David Price have both taken home the hardware in their careers, while Sale has been in the running essentially for his entire career. If a revamped slider helps Rodriguez get anywhere near that level, the Red Sox may have the American League’s most formidable rotation.