Madison Bumgarner's fresh start in Arizona hasn’t gone as planned so far.

The lefty signed a five-year, $85 million contract with the D-backs in the offseason after spending the first 11 years of his Major League career with the Giants. There were expectations that he’d continue to be the ace he’d been for the Giants for the majority of his career.

But he enters his fourth start of the season Sunday with a 7.04 ERA, third-worst among qualified starters in 15 1/3 innings pitched. In trying to ascertain what’s gone wrong, it’s hard to miss Bumgarner’s velocity.

A drop in velocity
Bumgarner’s three starts this season have been the three lowest of his career by average four-seam fastball velocity, at 87.9 mph on both Opening Day and July 29, and then 88.1 mph in his last start on Aug. 4. Previously, he’d averaged below 89 mph just once in his career -- on Sept. 8, 2009, his first career start, when he averaged 88.7 mph.

He’s averaging 87.9 mph on his four-seamer this year, and 85.7 mph on all fastballs (including his sinker and cutter). Bumgarner has never been a high-velocity pitcher, but he’s typically been at a higher level than this. Prior to 2020, his highest average fastball velocity was 92.7 mph in '15, and his lowest was 88.1 mph in '18.

In 2019, he averaged 89.6 mph on fastballs, meaning he’s lost 3.9 mph on fastballs from last season to this one. The only starter to lose more mph on his fastball from last year to this year is Mike Foltynewicz -- who went from 94.9 mph on fastballs last year to 90.4 mph this year, made one start for the Braves and was outrighted to the alternate training site.

But Foltynewicz only got a chance to throw 31 fastballs this year so far. If we impose a minimum of 50 fastballs, Bumgarner’s 3.9 mph drop is not only the largest among starters this year, but also tied for the second-largest from one season to a next by a starter on his fastballs since pitch tracking began in 2008, according to research from MLB.com's manager of baseball research and development Jason Bernard.

Largest avg fastball velocity drop from one season to next, SP since 2008
Min. 50 fastballs thrown
-5.4 mph: 2017 Hisashi Iwakuma (88.1 mph in 2016, 82.7 mph in 2017)
-3.9 mph: 2020 Madison Bumgarner (89.6 mph in 2019, 85.7 mph in 2020)
-3.9 mph: 2018 Ervin Santana (92.8 mph in 2017, 88.9 mph in 2018)

It’s worth noting that among the two pitchers with a fastball velocity drop this big, both ended up missing significant time due to injury -- Santana with a finger injury and Iwakuma with shoulder problems that eventually ended his Major League career.

What is going on here?
Bumgarner has said himself that he isn’t exactly sure. “Your guess is as good as mine,” he said after his second start of the year. “It’s obviously different, but I try to do everything I could do to make sure I was going to be ready. I feel ready, I feel good.”

Speaking after his third start, Bumgarner had more of the same to say -- that he hasn’t undertaken any changes in his process, and he’s still throwing the way he has in the past.

“I'm trying as hard as I can to get everything dialed in and get it right and get where I want to be,” he said. “And I think everybody's doing the same.”

Bumgarner injured his shoulder in April 2017 and each of his four seasons with the lowest average fastball velocity have been since then, each under 90 mph. Prior to that, he’d averaged at least 91.3 mph on fastballs in every full season of his career. It’s possible that the shoulder injury affected his ability to throw harder, but he’d leveled off from 2017-19, before dropping further this year.

That could raise concerns about another physical issue, but the team has said there’s no indication he’s currently injured, and he has said the same, saying he’s been replicating the same process.

It is worth noting that the past six months have been atypical, with pitchers ramping up in Spring Training only to stop and then get ready for the season over the shorter Summer Camp period. Bumgarner’s velocity was in the 90s in Spring Training, and the circumstances since then could certainly be playing a role here as well.

Lower velocity, worse results?
So far this season, opponents are hitting .265 in at-bats ending on Bumgarner’s fastballs, with a .490 slugging percentage. That batting average would be the highest on his fastballs since 2011 (.267), and the slugging his highest since 2010 (.507).

Of the 15 hits he’s allowed so far this season, all but two were on fastballs, including two doubles and three homers. Only six pitchers have allowed more hits on fastballs this season.

Adding to the concern, it’s possible Bumgarner has even gotten lucky. The expected slugging percentage against his fastballs, based on the quality of contact, has been .613 -- 123 points higher than his actual mark. Only six pitchers have allowed a higher xSLG on fastballs so far this season (minimum 35 at-bats ending on fastballs).

Adjustments
We don’t know how long this will go on for Bumgarner -- maybe his velocity will return, but he may have to pitch with this for the rest of the season, if not longer. But the question is, what happens then?

Bumgarner may have to rely on his other pitches more. Already, he’s been using his curveball 22.5% of the time, after using it 18.3% of the time last year. He's used his curveball almost as much as 2018, but it’s different when the reliance is due to ineffectiveness of other pitches.

Location will be even more important, too. He’s currently throwing 45.8% of his pitches in the zone, the lowest of his career, but that part of the game plan would likely need to change. Further to the point on location, he’s thrown 19.6% of his pitches into the chase zone, also the lowest of his career. It stands to reason he’d need to throw in the zone more overall, then be more specifically in that chase region when he is outside the zone, to have the most success.

Can this work?
It’s not easy, but yes. Here are a few examples Bumgarner can look to.

Dan Haren
Haren averaged 91.2 mph on fastballs in 2008, the first year of the pitch-tracking era, before dipping into the 80s in each season after that. From 2011-15 in the final five seasons of his career, he had a 3.90 ERA -- as a 30-year-old with diminished velocity. He poked fun at his velocity with his Twitter handle, iThrow88, and as luck would have it for Bumgarner, he’s currently a member of the D-backs’ baseball operations staff as a pitching strategist.

Jered Weaver
Weaver’s highest average fastball velocity in the pitch-tracking era was 90.8 mph in 2008. In 2013-14, his first two seasons in his 30s, he had a 3.45 ERA in 58 starts -- while averaging 87.1 mph on fastballs in '13 and 86.9 mph on fastballs in '14.

CC Sabathia
Sabathia averaged as high as 94.8 mph on fastballs in both 2008-09, but averaged 90.2 mph or lower in each season beginning with 2014, his age-33 campaign. Sabathia posted sub-4.00 ERAs in 2016, ‘17 and ‘18, and pitched until he was 39, averaging 88.5 mph in his final season in 2019.

Bumgarner isn’t used to throwing 96 mph, so this change isn’t as stark as it could be, but it will definitely continue to require adjustments for him to succeed in his new velocity echelon.