The Los Angeles Dodgers are a team in trouble. They’re 13-17, eight games behind the division-leading Diamondbacks, and even the internet’s least-excitable brand of playoff odds, at FanGraphs, now sees them as underdogs in the NL West. Although they won Wednesday, it cost them starter Hyun-Jin Ryu, who joins the list of L.A. wounded. Shortstop Corey Seager, the franchise’s most valuable position player since 2015, is out for the season with a sprained UCL that will require Tommy John surgery, and Justin Turner, who ranks second over that span, still hasn’t played (although he may return this month). Yasiel Puig and Logan Forsythe are sitting on the disabled list with matching OPS+ figures of 41, and even closer Kenley Jansen has been hit harder than usual amid concerns about diminished fastball speed.

The incomparable Clayton Kershaw is not part of the problem. However, he’s looking like less of a solution to L.A.’s ills than he has in the past. The Dodgers have won only two of Kershaw’s seven starts this season, and while the blame for those losses lies more with the lineup than Kershaw, who’s received only three runs of support, on average, the lefty is no longer a lock to be dominant every time he takes the ball. Kershaw’s ERA is still stellar by mortal-major-leaguer standards, if not by his own—his current 2.86 mark would, incredibly, be very close to his worst-ever full-season ERA, and would snap his nine-season streak of annually lowering his career ERA—but there are signs that the 30-year-old’s stuff has slipped. Though the future Hall of Famer remains a formidable pitcher, we’re probably past Peak Kershaw, which may make for a fascinating financial calculus as Kershaw’s decision about whether to opt out of the final two years of his contract at the end of the season draws near.

Of the 83 pitchers who had thrown at least 30 innings through Tuesday, Kershaw’s Deserved Run Average—Baseball Prospectus’s advanced assessment of a pitcher’s holistic contributions to run prevention—ranked 37th. Kershaw has pitched only seven games this season, so we’re still dealing with a fairly small sample. But he hasn’t been this ineffective in any other equal-sized regular-season sample since his rookie year, as evidenced by this graph of his rolling seven-game park-adjusted FIP marks over the past nine-plus seasons. The higher the line, the worse the pitching performance.

FIP is based on a pitcher’s strikeouts, walks, and home runs allowed. Kershaw’s strikeout and walk rates are at their lowest and highest levels, respectively, since 2013, when the leaguewide strikeout rate was significantly lower than this year’s. But the bigger problem has been Kershaw’s increasing susceptibility to homers and other hard-hit balls, like the one that Christian Walker crushed Tuesday for the longest home run on record against him.

The table below, which covers the seasons for which we have Statcast data, shows the increases in the rates of Kershaw’s batted balls that have been hit hard or have turned into Barrels or home runs, as well as the overall expected weighted on-base average of the balls in play he’s allowed, based on their exit speeds and launch angles.

Clayton Kershaw’s Eroding Batted-Ball Results Year LD+FB % Hard-Hit % Barrel % HR/Con % xWOBA Year LD+FB % Hard-Hit % Barrel % HR/Con % xWOBA 2015 50 24.5 3.3 2.8 0.316 2016 50.6 27.6 4.5 2.3 0.313 2017 52 26.5 6.3 5.2 0.351 2018 55 32.5 8.1 5.7 0.409

Those complex stats, which don’t even include the eight homers Kershaw surrendered in 33 innings last October, tell a simple story: Since the start of last season, and even more acutely in 2018, contact against Kershaw has done much more damage. To compound his problems, that contact has also become more common: Hitters this year have made contact on swings against Kershaw as frequently as they have in any season since 2009.

#Dodgers Clayton Kershaw has given up 3 HRs or less to LH batters in 6 of his 10 previous seasons. 3 to lefties in 1st 2 starts this season — Bill Plunkett (@billplunkettocr) April 4, 2018

The cause of Kershaw’s decreasing dominance isn’t hard to pinpoint: It’s his fastball speed. Kershaw’s command, at least, still seems to be intact: Among pitchers with at least 20 innings pitched, he ranked 15th last year and ranks fourth this year in called strikes above average, Baseball Prospectus’s proxy for command. But Kershaw’s four-seamer has slowed in three consecutive seasons, with by far the biggest drop coming this year.

Granted, it’s still spring, but in recent years, Kershaw hasn’t shown any tendency to throw harder as the season wore on; last year, in fact, he threw slower with each passing month during the regular season. This year, Kershaw’s average four-seamer speed has sunk slightly below the league baseline, even for left-handed starting pitchers alone. It would be very unusual for a pitcher’s stats to survive that reduction in speed unscathed. Studies performed by Mike Fast in 2010 and Jeff Zimmerman in 2014 found that for each mile per hour in fastball velocity lost, starting pitchers’ run averages tend to rise by about a quarter of a run. And Kershaw’s four-seamer has lost about 2.5 mph since his heyday, amid not only normal aging but also multiple lower-back injuries that sidelined him for a total of 113 days over the past two summers—more time than he’d lost to injury across all of his previous seasons combined.

It could be that Kershaw is pacing himself to try to avoid another late-season DL stint, but it’s looking more and more likely that his heater has simply lost its top range. As a rookie, Kershaw maxed out at 98, and until 2018, he’d exceeded 96 in every subsequent season. This year, though, he’s yet to touch 94.

Regardless of the reason for the fall-off—according to Dodgers beat writer Andy McCullough, “I mean, I’d always like to throw harder” is the most Kershaw has said on the subject—the loss of speed has taken a toll. Through Tuesday, 109 pitchers had thrown at least 150 four-seam fastballs, and only six had allowed a higher slugging percentage on the pitch than Kershaw’s .619. His .442 xWOBA with the pitch ranked right between Bryan Mitchell’s and Matt Harvey’s—not encouraging company, given that the latter has already lost his rotation spot, the former might be about to, and both have ERAs right around six. The latest blast against Kershaw’s four-seamer came on Tuesday in Arizona, where even the newly installed humidor at Chase Field couldn’t keep A.J. Pollock from knocking a centered, sub-90 mph Kershaw fastball over the fence.

The comeuppance of Kershaw’s heater has been swift. In 2013, his fastball was, according to FanGraphs’ pitch-type linear weights, the most valuable pitch in baseball—fittingly, directly ahead of Harvey’s fastball. (Life comes at you fast, or in this case, increasingly slow.) This season, Kershaw’s fastball has had negative value.

Kershaw is pitching as if he’s well aware that his fastball isn’t what it was. In an apparent attempt to optimize his pitch mix, he’s reduced his four-seamer rate and increased his slider rate to the point that his usage of the latter appears poised to surpass his usage of the former.

Of the 136 pitchers who had thrown at least 20 innings through Tuesday, only five had thrown fastballs of any kind—four-seamers, sinkers, and cutters combined—less frequently than Kershaw. As I noted last month, some pitchers, including the Diamondbacks’ Patrick Corbin, have improved their performance by moving away from their fastballs. In general, though, the pitchers who’ve benefited from less fastball-centric approaches didn’t have very effective fastballs in the first place. Kershaw had the most effective fastball. Take the best pitch away from the best pitcher, and even the greatest gets worse.

The good news for Kershaw, and the reason that he’s pitched as well as he has with a diminished fastball, is that he still has two other offerings that most other pitchers would commit crimes in order to throw. In 2016, Kershaw had the most valuable slider in baseball, and in 2015, he had the third-most-valuable curve. That season, Kershaw led the majors with 301 strikeouts, and the whiffs were distributed almost evenly among the three pitches, a testament to the depth of his arsenal. Neither the slider nor the curve has seen its speed drop off as dramatically as the fastball, but both pitches have continued to yield positive results despite Kershaw’s increased reliance on them and the decreased separation in speed between his fastball and his off-speed stuff.

It’s not out of the question, of course, that Kershaw’s missing speed could come back. Justin Verlander’s average four-seamer speed dropped off significantly when he was right around Kershaw’s age, and his results suffered, but his fastball subsequently bounced almost all the way back, as did his performance. But Verlander, whose fastball gained 2.4 mph between ages 31 and 34 and whose earlier velocity loss likely stemmed from a core injury, is the exception. Of the 45 other starters in the pitch-tracking era who’ve thrown four-seamers at both ages 31 and 34—the lucky ones, who didn’t move to the bullpen or wash out of the sport—37 lost speed, on average, between those two seasons, and only two gained as much as one mph. Kershaw’s sapped speed may be attributable to his back injuries, but back problems are notoriously tough to shake, and he probably can’t condition himself any better than he already has. When aging pitchers lose velocity—and they usually do—it’s often gone for good. Félix Hernández can testify to that.

Even if Kershaw’s elite fastball never returns, there are ways he could compensate. He’s already tried throwing lower in the zone, though that hasn’t solved his vulnerability to big flies. But he could become less predictable. In the past, Kershaw was highly reliant on his fastball when hitters were ahead: In 2016, he threw four-seamers 78 percent of the time on 2-0, 3-1, and 3-0 counts combined. This year he’s down to 57 percent fastballs in those counts, which in theory has made it more difficult for hitters to guess what’s coming. If Kershaw were still throwing his fastball as often as he used to, his stats would probably look more dismaying than they do.

That shift away from the fastball when Kershaw falls behind has had one undesirable side effect: Because the slider is no longer being used exclusively as a putaway option, the pitch has experienced a steep drop-off in whiff rate this year.

Even so, Kershaw’s increasing willingness to vary his pitching patterns should help keep hitters from feasting on his fastball. But in some ways, he’s still too predictable. In 2016 and 2017, Kershaw never threw a curveball when he was behind in the count. This season, he’s thrown two already. Progress! But not enough. If Kershaw is down to two above-average pitches, he’ll have to mix them even more unpredictably to maintain an edge. He could also try picking up a new pitch, like the cutter that’s helped prolong the career of CC Sabathia, another left-handed power pitcher whose four-seamer succumbed to age and injury. Kershaw has shown that he isn’t averse to experimenting, sporadically utilizing a lower arm slot that he learned from Rich Hill, although that new look hasn’t yielded great results.

As recently as last spring, there was no debate about the identity of the best pitcher in baseball. By last summer, Kershaw’s hold on the top spot was starting to slip: In late June, FiveThirtyEight’s Neil Paine pointed out that according to the site’s starting-pitcher ratings, Kershaw had recently been dethroned. In FiveThirtyEight’s current ratings, as provided by Paine, Kershaw ranks eighth, behind Justin Verlander, Corey Kluber, Max Scherzer, Stephen Strasburg, Chris Sale, Carlos Carrasco, and Luis Severino. It was inevitable that Kershaw would someday cede the top seed to a new crop of pitchers, but we didn’t think it would look like this; four of the seven higher-ranked pitchers are older than him.

In addition to deepening the Dodgers’ current divisional dilemma, the red flags in Kershaw’s outings over the past season-plus may put his next payday in jeopardy. The sport’s highest-paid player is signed through 2020 for a total of $65 million over the next two years and can opt out at the end of this season. Until recently, it seemed like a foregone conclusion that Kershaw would either work out an extension with the Dodgers or exercise his opt-out and land a long-term free-agent deal. One of those outcomes will probably still come to pass, but it’s getting easier to envision a scenario that won’t result in as massive a windfall as we might have thought. If Kershaw gets hurt again, or his fastball speeds continue to dwindle, or his peripherals prove to be more accurate indicators of the rest of his season than his sub-three early-May ERA, it may make teams wary of tying their futures to a pitcher past 30 whose stuff is slipping—even a pitcher who’s just treated us to one of history’s most dominant decades. But baseball would be better if he has a second wind.