The news that Corbin Carroll had suffered a broken hamate bone in his hand was not the way the D-backs wanted to start spring training. I guess the good news – if there is any – is that the injury happened at the beginning of the pre-season, minimizing the amount of regular season time lost. Indeed, with almost six weeks between the injury and Opening Day, he may not end up missing much time, if any at all. However, there is a common perception that even after the player returns, the injury can have a negative impact, particularly in regard to their power. According to orthopedic sports surgeon Dr Deepak Chona:
“The amount of time varies, but generally projects to six weeks after returning. Most likely, this timing correlates with the recovery of grip strength and control of the bat. This dips after surgery (1) because of the generalized trauma/swelling to the muscles of the hand and (2) because the part of the bone (called the hook of the hamate) that they cut out to treat the fracture is involved in generating grip force as well.”
Is there statistical data to back up a drop in power? To see if there is, I used Fangraph’s Injury Report tool to find the occurrences of broken hamates in the majors over the last five years. There were seventeen, including some to names you might recognize – backup catcher James McCann suffered the same injury, while on the Mets in 2022. Three of those took place in September, and the players concerned didn’t return that year. So I excluded those from the sample, because they will have been well past the period of weakness described by Dr. Chona, by the start of the following campaign.
Firstly, the average date between the event and the player coming off the Injured List was 61 days. That’s a little longer than expected, but is skewed by two players who each spent more than a hundred days on the IL. Half the fourteen players returned in seven weeks or less – which fits in with the 6-8 week time-frame often reported – the quickest being Emmanuel Rivera’s 36 days. So there is a chance that Carroll could indeed be back on the active roster in time for Opening Day, though it is more likely he will miss some time. But what might his performance be like when he comes back?
To look at that, I took the final thirty games for each player (which may be partly or all from the previous season), and compared their numbers there, against the first thirty games after their reactivation (or up until the end of the year). Angel Martinez and Emmanuel Rivera had made zero and two major-league appearances respectively before suffering their fractures. On the other hand, Rafael Marchán did not appear in the majors at all in 2023 after coming off the IL, and Mike Trout played only one game post his injury. So I skipped all four of their numbers entirely, even though this does reduce our sample-size to ten.
I then took the quick and dirty approach of simply averaging the triple-slash lines plus OPS. To be entirely accurate, I should have weighted these by PAs, but life’s too short, and this isn’t a doctoral thesis, so I’m happy with a “good enough” approach. Again, I do caution that this is a very small sample, and every individual case is going to be different. Past performance is no guarantee of future production, and please consult with your financial advisor before making any decisions based on these numbers. But the results we have, are as listed in the table below:
Before hamate: .192/.268/.328 = .596 OPS
After hamate: .217/.293/.358 = .651 OPS
Hence the disclaimer above. Because otherwise, I’m sure there would be a rush of players running off to get their hamate bones removed, in order to boost their batting average by 25 points. Hey, Tommy John surgery makes you throw harder, doesn’t it? But if we look in particular at the isolated power metric of ISO (slugging percentage minus batting average), it hardly changes: .136 before, and just five clicks higher afterward, at .141. With a sample size of less than three hundred games on each side, that doesn’t seem statistically significant. While Dr. Chona’s logic makes sense, over the past five years it doesn’t appear that hamate injuries have led to a decline in power post-procedure.
It is possible that this is a relatively recent phenomena, resulting from improvement in care after the operation and rehabilitation processes. We’ve seen this in regard to Tommy John, which was once seen as the kiss of death to a pitcher’s career, but is now “super easy, barely an inconvenience.” Ok, I exaggerate, but it does take time for broader perceptions to catch up with advances in medical technology and procedure. It is possible that, previously, hamate surgery did have an impact on player power, but that no longer seems – at least, necessarily – to be the case. Which is good news for Corbin Carroll and the Diamondbacks.