Chris Sale lost his fastball. Now the Red Sox could lose the AL East.

Sale is 0-3 with a 9.00 ERA, his 13 earned runs in 2019 more than a third of the 37 runs he allowed over 27 starts all of last year. He is striking out a career-low 13 percent of batters faced and walking almost 7 percent, his highest rate since 2012 as a member of the Chicago White Sox. His swinging strike percentage (10.5 percent) is also at its lowest point since 2012, and hitters are making better contact against him than they have in the past four years, hitting the ball on the sweet spot of the bat once out of every 12 balls put in play.

The most concerning stat for Sale, and the Red Sox, is his four-seam fastball velocity, which has tumbled from an average of 95.6 mph in 2018 to 91.5 mph this season, the most noticeable dip occurring after suffering a shoulder injury late last season. The injury could be a lingering issue but that didn’t stop the team from inking the 30-year-old to a five-year, $145 million contract extension this winter.

Regardless, the effectiveness of Sale’s fastball is nowhere near where it needs to be right now. Batters aren’t swinging as much on his fastball because Sale isn’t throwing it in the zone as often – down from 53 percent to 41 percent in just one season. The swinging strike rate on this pitch is also a paltry 1.3 percent.

This chart displays Chris Sale’s fastball and his rate of landing it in the strike zone, as well as his percentage of swinging strikes on his fastball.

“The stuff, we know, wasn’t there,” Cora told Steve Hewitt of the Boston Herald. “I think the off-speed pitch is the one that, he’s not consistent with it. Everyone talks about the fastball, but for me, it’s the slider. It’s the best slider in the game, and right now it’s not that.”

Sale’s slider, used against both right- and left-handed batters, has been a commanding pitch. From 2017 to 2018, batters hit just .181 against the pitch with 141 strikeouts over 276 at-bats. This year, batters are hitting .217 against it with four strikeouts in 23 at-bats, illustrating it is still an effective offering. And its decline is nowhere near the decline of his fastball. For example, his slider saved the team over two runs per 100 times thrown in 2018, which has dropped to break even in 2019. His fastball, on the other hand, saved the team nearly a run every 100 times thrown last year but is now costing the Red Sox six runs per 100 times thrown in 2019 – the worst rate among starting pitchers.

Chris Sale, 95mph Fastball.

In case you were wondering…. pic.twitter.com/3byoiYK18i

— Rob Friedman (@PitchingNinja) April 9, 2019

The rest of the starting rotation also doesn’t appear to be able to pick up the slack. It has a combined 6.17 FIP – a team’s ERA over a given period of time if the pitcher were to have experienced league-average results on balls in play and league-average timing – second worst only to the Baltimore Orioles (6.41 FIP) largely in part to allowing 28 more runs to score than we would expect given the number of outs and men on base during each plate appearance, the most in the majors and eight more than the next worst rotation, the Chicago White Sox.

Here’s the bottom line: Sale was projected to be the most valuable pitcher in the AL this year (5.8 wins above replacement) and the second most valuable pitcher in the majors after New York Mets ace Jacob deGrom. Those projections have since been revised to 4.3 fWAR in 2019. One win may not sound like a lot but consider how tight the race is in the AL East. New York has a 57 percent chance to win the division with 95 wins, the Tampa Bay Rays have the next-best chance at 25 percent (91 wins) followed by Boston (18 percent, 89 wins). The Red Sox are now barely above a 50/50 chance to make the playoffs, per FanGraphs. They were given a 90 percent chance to make the playoffs at the start of the season.