Thoracic Outlet Syndrome Fells Archer

If the 2020 season does happen — and right now, that’s an open question — it will be without Chris Archer. The Pirates announced on Wednesday that the 31-year-old righty underwent surgery to correct for thoracic outlet syndrome, ruling him out for whatever transpires this season, and perhaps ending his time in Pittsburgh given his contract situation. Given the track record of pitchers who have undergone the procedure, we can only hope that this doesn’t mark the end of the two-time All-Star’s run as an effective pitcher.

As I’ve written before, thoracic outlet syndrome is caused by a compression of the nerves and/or blood vessels somewhere between the neck and the armpit. Symptoms commonly include numbness or tingling in the fingers and hands, or fatigue or weakness that doesn’t go away with physical therapy and rest. Pitchers tend to be particularly vulnerable to TOS because of their repetitive overhand movements and the way their arm muscles build up. The condition is generally remedied by the removal of a cervical rib and two small scalene muscles.

Archer, whom the Pirates acquired from the Rays on July 31, 2018 in exchange for outfielder Austin Meadows and pitchers Tyler Glasnow and Shane Baz (the latter as a player to be named later) — a steal of a deal for Tampa Bay, the way things have gone — endured the worst season of his eight-year career in 2019. Though he struck out a respectable 27.2% of hitters faced, his walk and home run rates jumped significantly from their 2018 levels, the former from 7.7% to 10.5%, the latter from 1.15 per nine to 1.88. Both of those were career highs, as were his 5.19 ERA and 5.02 FIP, which were respectively 20% and 13% worse than league average. Per Pitch Info, his average four-seam fastball velocity fell a full tick from 2018 (95.3 mph to 94.3 mph) and was down 1.5 mph relative to ’17 and 1.9 mph relative to ’15.

Amid that grim litany, Archer actually pitched significantly better after the All-Star break than before:

Unfortunately, his renaissance was cut short due to injuries. Having already served 18 days for right thumb inflammation in late April and early May, he left his August 20 start after one inning due to right shoulder inflammation. Though he began rehabbing towards a return, he was shut down for the season in mid-September. After the season, the Pirates picked up his $9 million option and termed him “healthy and full systems go” as of mid-December, but he was scratched from his first scheduled spring start on February 24 due to neck discomfort. He made his spring debut on March 6 with four strikeouts in a pair of scoreless innings against the Blue Jays, but didn’t get to pitch again before the COVID-19 shutdown.

In a conference call with reporters on Wednesday, general manager Ben Cherington and director of sports medicine Todd Tomczyk noted that Archer had indicated further neck discomfort before the closure of camp but remained on a monitored throwing program after the closure. He experienced some symptoms common to pitchers who experience thoracic outlet syndrome but not all of them, and not immediately after throwing; sometimes, it was hours or days later. Via MLB.com’s Adam Berry:

“What is consistent with TOS is the inconsistencies, so that’s what makes it sometimes challenging to make a clear-cut diagnosis,” Tomczyk said. “But Chris is and was very diligent with marking down what he felt, when he felt it, to help himself and help us and the physicians really pin down the correct diagnosis so we could help him move forward.”

Doctors determined that his throwing shoulder and elbow were structurally sound, Tomczyk said, and experts initially ruled out the possibility that he had thoracic outlet syndrome. However, Tomczyk noted that it can take time for doctors to definitively diagnosis the syndrome; reliever Nick Burdi visited multiple doctors before having a similar surgery last year, for instance.

Archer won’t be able to pitch this year, leaving the Pirates to decide on how to handle his $11 million option for 2021; the buyout is $250,000. For the tight-fisted franchise whose estimated 2020 payroll is only $61 million, that seems like a long shot, even given his upside. “We won’t have games to evaluate, but there will be other information that we have at that time that we don’t have now. So we’ll just want to take all the time we have,” said Cherington.

Complicating matters for the Pirates and Archer is the sad fact that unlike Tommy John surgery, the range of outcomes is quite wide when it comes to pitchers who have undergone surgery to correct TOS, and there aren’t a ton of success stories. Updating the data I pulled together for my May 2018 piece on Phil Hughes:

I’ve made the table sortable, so you can see how things shake out in a variety of ways. It’s worth noting that Archer is in the oldest quartile here, and is fourth in pre-surgical innings; the three pitchers ahead of him ranged from 17 post-surgical innings to 1,253.1, which isn’t much help in terms of forecasting. More helpful was sorting the pitchers into three buckets based on the age at which they had the surgery:

The youngest group of pitchers fared the best afterwards, throwing more post-surgical innings than pre-surgical ones, and seeing some improvement in performance. The oldest bunch, the group of which Archer will be part, saw some decline, but the group in the middle was a wasteland even apart from the fact that three of its eight pitchers never made it back to the majors. Nearly half the innings of that cohort belong to Harvey and Wells, both of whom served as piñatas for major league hitters following surgery. Their outsized effect on that group should serve as a reminder that these are small sample sizes, and so an extreme performance here or there can skew the numbers. On that note, if I remove Rogers from the oldest group simply to note the effect his success has on the overall numbers, the innings averages drop to 1,162 pre-surgery and 144 post-surgery; while the ERA- and FIP- for the former remain the same, those for the latter jump to 112 and 120 — roughly as (in)effective as the middle group.

Admittedly, this is a pretty crude analysis that’s only boiling things down to run prevention and its components. It may well be more instructive to look more closely at things like pre-surgical velocity and spin rate, at least for the more recent pitchers who have that data, but that comes at the expense of sample size. It’s possible that Archer’s ability to throw in the mid-90s increases his chances of a successful return compared to a pitcher like Hughes, whose velo was in the low 90s when he went under the knife. Maybe it’s significant that Archer was pitching well just prior to being sidelined, rather than enduring a grim slog towards the injured list. Perhaps the variations in type of TOS — neurogenic (roughly three-quarters of cases, including Archer’s), venous, or arterial — are significant when it comes to post-surgical outlook, though we simply don’t have classifications for most of the pitchers above. There’s a lot we don’t know, however, and so we can only hope that the comeback of a pitcher who once rated among the game’s most promising goes well.