What batters had the largest gain in their OPS in the 2nd half of a season compared to the 1st half?

I used bases.chat, the baseball AI program created by Ted Ingram.

The minimum PA requirement was 200 or more in each half. The program considered the the first half ended on June 30, no matter what the year. Notice that Bobby Thomson (1951) is in the leader list. The search covered all years from 1898-2025. 

I initially did this query because I wanted to see where Christian Yelich of 2018 would rank. He had a tremendous second half and won the MVP award. His gain was .304 (.835 to 1.139). Very good but well below the top 10 here. It did not even make the top 10 from 2001-2025 (10th was .352).

Rank	Player	Season	1H OPS	2H OPS	Gain
1	Johnny Mize	1938	0.756	1.219	0.463
2	Jose Ramirez	2019	0.634	1.078	0.444
3	George Brett	1990	0.656	1.089	0.433
4	Mike Hargrove	1979	0.572	0.984	0.412
5	Bobby Thomson	1951	0.724	1.130	0.406
6	Luis Rengifo	2023	0.590	0.980	0.390
7	Albert Belle	1998	0.863	1.251	0.388
8	Willson Contreras	2023	0.672	1.059	0.387
9	Luke Easter	1952	0.659	1.044	0.385
10	Eugenio Suarez	2024	0.591	0.974	0.383

The Phillies lost to the Dodgers on Tuesday with the final play having the two base runners on 2nd and 3rd getting tagged out resulting in a 0.558 Win Probability Added for the Dodgers. Where does this defensive WPA rank all-time?

With 1 out in the bottom of the 9th the Dodgers were ahead 2-1. Phillies had runners on 2nd & 3rd. The batter hit a ground ball to the 3Bman. He throws home as the runner on 3rd went home.

But the runner ran back to 3rd seeing that the catcher had the ball. The catcher runs him back to 3rd. But Betts ran in from SS. He took a throw from the catcher and tagged out the runner.

By this time the runner on 2nd had run to third but then ran back to 2nd base when he saw the original runner retreat to 3rd base. 

As soon as Betts tagged the original man on 3rd he turned and threw the ball to the 2Bman who tagged the runner trying to get back. Game over.

 

Here is a video 

 

Here is a video posted by Todd Zolecki 

 

This link from Stathead has the results from the search For year 2026, Involving Philadelphia Phillies, Game-Ending, Sorted by Championship Win Probability Added.

 

If you sort by WPA, this play is the highest listed.

 

This link from Stathead has the results from the search In years 1903 to 2026, requiring WPA >= .5, Sorted by Win Probability Added. 

 

I had selected "non-SO outs->(to Pos) as the Event Type. I also used the "All Outs" option under "Double/Triple Plays." Here are the top plays:

 

Rk	Date	WPA	Bat Tm	Def Tm
1	7/15/1930	0.572	PHI	STL
2	9/25/1948	0.571	BSN	NYG
3	9/10/1973	0.571	BAL	BOS
4	4/8/2018	0.57	NYY	BAL
5	5/1/2000	0.57	CLE	NYY
6	8/4/1921	0.568	BOS	CHW
7	5/11/1997	0.566	MIN	TOR
8	9/24/2000	0.566	BOS	BAL
9	7/1/1939	0.564	STL	PIT
10	8/27/1996	0.564	COL	CIN
11	9/13/1982	0.564	BOS	CLE
12	9/16/1930	0.564	BRO	STL
13	7/2/2021	0.563	OAK	BOS
14	7/21/1999	0.558	CLE	TOR

 

So it looks like this play by the Dodgers ties for the 14th highest WPA ever in the Stathead databse by a defensive team. Also, the search results will allow you to go to to the box scores of the games and it also tells you what the play was and all the relevant situational details. 

 

This most recent play from the Dodgers-Phillies game did not show up on these search results. I asked BB Ref about this and they told me 

"It looks like the event is coded as a "Fielder's Choice", and for some reason, that doesn't show up when filtering for "Non-SO outs". That seems like an error in the codebase, so I'll have our engineering team look into it." 

Also, the actual top 4 results you will see if you click on the link are WPAs greater than one (which makes no sense). I omitted those in the table above. BB Ref told me that "I'll have our engineering team look into the problem" about this issue as well. The 5th one is actually a play in which a run scored on an error on the final play of the game and the batting team won.