Brandon McCarthy’s pitch this offseason was probably going to be one of faith. He was going to have to convince teams that he was what his fielding independent pitching said about him, not what the results did. In 78 innings with the Yankees, the whole tone of the presentation changed.

Since his trade from Arizona, McCarthy’s ERA has been cut nearly in half, from 5.01 with the Diamondbacks to 2.54 in New York. His walk and strikeout rates have improved slightly, but they were already fine; it’s been the BABIP and a change in his repertoire from more two-seamers to more cutters and four-seamers that have made the difference.

It’s almost always a combination when things turn from going so wrong to going so right. It’s hard to create a 2.5-run swing without being a little unlucky at first and a little lucky in the end, but it’s also hard without any actual changes.

McCarthy’s rise after a midseason trade is one of the best baseball has seen in the past quarter century. If he continues his good work in his start tonight, it has the chance to crack the top 5.

On the list of most improved after a midseason trade, we have a couple who were starting out so bad there was really no place to go, a couple who started fine and became historic, and some just like McCarthy. Here are the biggest post-trade breakouts, starting with the pitchers.

Pitchers (Since 1988, biggest ERA improvements, min. 50 IP for each team)

5. Woody Williams, 2001, 4.97 ERA for Padres, 2.28 ERA for Cardinals
Traded for Ray Lankford on August 2nd

A pitcher leaving San Diego probably isn’t the first place you expected this list to be heading. It wasn’t Petco Park, but the old Q was a bad hitter’s park too. Williams’ walk and strikeout rates were essentially identical before and after the trade—each within 0.1 per nine innings of being exactly equal—but he slashed his BABIP by 84 points and cut his home run rate in half, and that was most of the problem. He still ended up finishing fourth in the NL in home runs allowed that year, but he was a big part of helping the Cardinals finish 17-5 and grab the NL wild card.

4. Andy Ashby, 1993, 8.50 ERA for Rockies, 5.48 ERA for Padres
Traded with Brad Ausmus and Doug Bochtler for Greg Harris and Bruce Hurst on July 27th

This is more like what we expected this to look like, and for Ashby, who was cursed with a rotation spot for the Mile High Stadium Rockies, there was no place else for his stats to go. Even by ERA+, a ballpark-adjusted metric, this is one of the 50 worst seasons of all time for a player who pitched 120-plus innings.

3. Randy Johnson, 1998, 4.33 ERA for Mariners, 1.28 ERA for Astros
Traded for John Halama, Freddy Garcia and Carlos Guillen on July 31st

The best deadline pitching acquisition of all time, he made his first start in the National League on August 2nd and finished seventh in the NL Cy Young voting. (He had more WAR than the guys who finished second and fifth.) He also got MVP votes as he helped the best team in Astros history to 102 wins. Some of it was home run suppression, and the Astrodome helped, but you don’t just home-run-suppress your way to going seven-plus innings and two or fewer runs in 10 of 11 starts.

2. Jeremy Guthrie, 2012, 6.35 ERA for Rockies, 3.16 ERA for Royals
Traded for Jonathan Sanchez on July 20th

There’s leaving Colorado and having your regular rate stats improve, and then there’s leaving Colorado and actually improving, and the latter is what Guthrie did. He cut his walk rate by almost 40 percent, raised his strikeout rate by more than 20 percent, and yada, yada, yada, here’s a $25 million contract. For this low-strikeout pitcher, who began to look even more extreme as the game changed around him, this is just about a best-case scenario.

1. Dennis Rasmussen, 1988, 5.75 ERA for Reds, 2.55 ERA for Padres
Traded for Candy Sierra on June 8th

Everything improved for the big lefty, whose 148 innings with the Padres after an early-season trade were the best stretch of a 12-year career. His career was pretty unremarkable for a guy who pitched 1,460 innings. No All-Star Games, no Cy Young votes, no playoff appearances. But after the trade that tops the list, it was told that it was pretty remarkable that his career even started.

Hitters (Since 1988, biggest True Average improvements, min. 150 PA for each team)

5. Matt Holliday, 2009, .288 TAv for Athletics, .367 TAv for Cardinals
Traded for Clayton Mortensen, Shane Peterson, and Brett Wallace on July 24th

Given the hindsight of knowing what everybody became, for the Athletics to flip Carlos Gonzalez, Huston Street, and Greg Smith into that trio 400 plate appearances later looks like a spectacular case of buying and selling at the wrong times. With Holliday approaching his first payday and the A’s being the A’s, the Cardinals found themselves the beneficiaries of a home run surge, a BABIP surge (his walk and strikeout rates both actually got worse), and comfort when it came time to negotiate.

4. Adam LaRoche, 2009, .265 TAv for Pirates, .346 TAv for Braves
Traded twice, July 22nd and July 31st

LaRoche wasn’t actually traded from the Pirates to the Braves, but Atlanta was there to capitalize when the intermediary Red Sox, who had acquired LaRoche for prospects nine days before the deadline, wanted to upgrade on their upgrade. There was going to be a bit of a jam at first base with the acquisition of Victor Martinez, so they got younger with Casey Kotchman. LaRoche hit .325/.401/.557 playing every day for Atlanta. His 19 plate appearances with Boston exactly matched the more famous Mike Piazza Marlins tenure.

3. Randy Winn, 2005, .270 TAv for Mariners, .353 TAv for Giants
Traded for Jesse Foppert and Yorvit Torrealba on July 30th

When I first pitched this story idea to Sam Miller, he was mostly excited because of the possibility of tales of Randy Winn’s 2005 season. So I’m turning this one over to him:

Winn was a well-known pretty good player, but he was a very particular type of pretty good player. In six seasons before the Giants traded for him, he’d never hit more than 14 homers; in the five that followed, he’d never hit more than 14 homers; but in the two months after the Giants acquired him, he hit 14 homers, 13 from the left side, while playing in a home ballpark that muted left-handed power. He had 51 hits in the final month. It was absolutely glorious, the one bright spot in a dreadful, going-nowhere season. And then, of course, Brian Sabean did the one unthinkable thing: He signed Winn (who was already under team control for 2006) to a long extension, seemingly based on that two-month stretch. That was the start of what’s now a signature Sabean move: Trade for a player, get an unexpectedly strong second half or bounce-back season, then sign him to a new, longer contract to cover the regression years. Aubrey Huff, Marco Scutaro, Pat Burrell, Angel Pagan, and Javier Lopez all pretty much fit the formula. Some of those guys are World Series heroes now! Randy Winn is not. —SM

2. Chris James, 1989, .171 TAv for Phillies, .268 TAv for Padres
Traded for John Kruk and Randy Ready on June 2nd

This was still a horrible trade for San Diego, but at least if James is on the list, they got a good half season out of him. After being swapped for the Phillies’ future three-time All-Star and first baseman on their pennant-winning team, James was involved in another big-name deal just six months later. He was thrown into the trade that sent Sandy Alomar and Carlos Baerga to the Indians in exchange for Joe Carter.

1. Manny Ramirez, 2008, .305 TAv for Red Sox, .425 TAv for Dodgers
Traded in a three-team trade that included the Pirates on July 31st

Manny’s give-up year in Boston that got him sent cross-country would have been Derek Jeter’s best offensive season this century. And that was the baseline for the biggest midseason improvement after a trade. That’s how well he hit in Los Angeles, going .396/.489/.743 in taking a narrative-driven fourth in the NL MVP voting and an absurd .520/.667/1.080 in two playoff series that year. Actually, it was all absurd.

Thanks to Rob McQuown and Baseball Reference for the research assistance.

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"The best deadline pitching acquisition of all time"? All due respect to the Big Unit, but I say that award goes to CC Sabathia (3.83 ERA in Cleveland, 1.65 ERA in Milwaukee) remembering that he was pitching complete games every three days for the Brewers.
He was awesome, and I thought about him and also Rick Sutcliffe, who won a Cy Young in the NL after being traded from Cleveland to the Cubs midseason.

Neither of them was acquired within even three weeks of the deadline, and that's why I worded the sentence like that. Both Sabathia and Sutcliffe deserved mention somewhere though, so I'm glad you brought CC up. That was a fun run. -Z
And I had forgotten about Sutcliffe, what with my recency bias. Thanks for reminding me about that awesome performance.
Everyone remembers who the Tigers gave up to get Doyle Alexander in 1987. Pretty good fella by the name of John Smoltz.

A lot less people remember that Alexander went 9-0, 1.53 in 88 innings for the Tigers. Who won the AL East. It's not like they got nothing in return.
Clearly McCarthy is benefiting from Jeter's defense.