We Love the MLB Trade Deadline — But Is It Overrated?

Every year, we obsess over who buys, who sells and who stands pat. Sometimes, it moves the needle — but probably not as often as we think.

Not every deadline pickup makes as much of a difference as CC Sabathia did in 2008. (Darren Hauck/Getty Images)

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Baseball’s trade deadline (July 31 at 6 p.m. ET) is officially less than a week away, and that means it’s time to debate the buyers and sellers, scouring the Big Board for pickups that fit with contenders’ biggest needs. The Athletic calls it “the best week of the regular season”, and they’re not wrong. Other than Opening Week, no other point on the MLB calendar — before October, that is — delivers more excitement and promise than the next handful of days.

I am far from immune to all the rumor-mill enthusiasm. Quite to the contrary: I did an all-day live blog on Deadline Day last year — tracking Wins Above Replacement added and subtracted for each team in as close to real-time as I could — and the Doyle Number, a throwback to my old FiveThirtyEight days, is an annual staple of my deadline-week calculations dating back a full decade.

What’s the Doyle Number? I explain it more here, but it’s a metric designed to help MLB teams decide whether they should buy or sell talent at the trade deadline. It estimates the amount of long-term value a team should be willing to give up (over the next six years)¹ in exchange for gaining 1 extra win this season, if their goal is to maximize total overall World Series wins. Teams above 1.0 — where current wins are worth more than future ones — should probably consider buying; teams below 1.0 should probably sell.

Just for fun, here’s a table of this year’s Doyle values (as of Thursday):

So clearly a lot of thought and planning has to go into every single deadline move. And sometimes, the trade deadline can have a huge impact if a freshly acquired star goes on a tear with his new team.

That’s what happened when Hall of Famer CC Sabathia joined the Brewers in July 2008. Traded from Cleveland, Sabathia made 17 starts for Milwaukee and carried the club down the stretch, going 11-2 with a 1.65 ERA and a sparkling 5.1 strikeout-to-walk ratio. He racked up 5.5 WAR — more than any other Brewer that year, despite playing only a half-season in Milwaukee — and helped snap the team’s 26-year playoff drought. Sabathia even finished sixth in NL MVP voting, the highest of any pitcher, despite making more starts in the AL than he did in the NL.

That gave Sabathia the most WAR for a midseason acquisition since 1986, when MLB standardized the trade deadline to July 31 — using a definition that includes only players who joined a new team after the season began and played fewer than 50 percent of games with that team:

For those players and their new squads, the deadline was far from overrated. But after doing this exercise for hockey’s trade deadline, tracking how a team’s net talent acquired at the deadline predicts its performance over the stretch run and beyond — it doesn’t, at least not really — I realized I hadn’t done the same thing for baseball, instead just acting like the deadline was of more importance in MLB than the NHL.

At that point, I knew I had to do a version of the same methodology, looking at baseball. So I took each team’s net WAR added minus subtracted from the players who qualified for our CC-led list above, and looked at how it correlated with a team’s change in Elo rating from July 31 onward in each full regular season² since 1986:

The correlation ended up being just 0.208, which was actually even lower than the NHL’s 0.247 mark when I looked at it back in 2024. There is certainly some small positive effect to loading up, but for each net WAR added via deadline (or deadline-adjacent) moves, a team’s Elo rating improves by 2 points. To get enough Elo to close the 13-point gap between, say, this year’s Brewers and Cubs — just as an example — you’d need to add 6 net WAR, which was more than 99.8 percent of teams in our sample. (Remember, Sabathia — the GOAT of in-season pickups — only had 5.5 for the ‘08 Brewers.)

There usually just isn’t enough star power on offer to make a huge dent, and it’s difficult to predict which players will have that transformative quality anyway.

Now, maybe you might be thinking — as I did — that many of these moves are really about the playoffs anyway, not the end of the regular season. But World Series winners in our sample actually added less net WAR at the deadline on average (+0.93) than playoff teams who didn’t win the championship (+1.01). And in a logistic regression attempting to predict a playoff team’s odds of winning the World Series based on two factors — pre-deadline Elo and net WAR added at the deadline itself — the former was a legitimate predictor, while the latter was actually irrelevant at best and negative (its coefficient was -0.029) at worst.

Perhaps that’s because true contenders need less help at the deadline than fringe playoff squads to begin with, so the big swings are taken by worse teams. But if that’s true, it doesn’t exactly help make the case for the deadline’s importance when the most significant deals are desperate moves by teams on the playoff bubble, rather than the final pieces of a championship puzzle.

But still, even if the deadline isn’t the seismic needle-mover we like to imagine, the trades do matter on some level — not because they alter the complexion of a pennant race as much they represent the uncertainty and excitement of the stretch run and the postseason push. They provide a jolt of much-needed possibility in these dog days of summer. And judging from the huge divide between potential buyers and sellers in our Doyle chart, plus the wide-open state of this year’s contenders in general, we could be due for a flurry of activity next Thursday.

Will all — or even most — of it end up mattering? No. But the chance to snag the next Sabathia, however slim, makes the frenzied ritual feel worth it.

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Filed under: Baseball, Statgeekery

1. With adjustments for roster age, payroll, farm-system quality and other forward-looking indicators.

2. Excluding the strike year of 1994 and the pandemic season of 2020.