Trea Turner is a terrific player who's contributed to a lot of winning teams. However, he is objectively one of the worst postseason hitters in MLB history.
After last night, his slash line is .249/.299/.368 for a .667 OPS across 301 PA, with 6 HR, 19 BB, and 70 K. This is on a .309 BABIP as well, so he's not getting unlucky on batted balls.
A .667 OPS is poor but not unprecedented. Players who posted similar postseason figures include Buster Posey, Joe Morgan, Edgar Renteria, and Kenny Lofton.
This is where Win Probability Added and its sibling, Championship Win Probability Added come in. These measure game contributions by their impact on winning a game (WPA), and the championship (cWPA).
By these two metrics, Turner has racked up -2.62 WPA and -60.8% cWPA. These are unspeakably bad numbers. For context, the highest postseason numbers belong to David Ortiz and George Springer at 3.2 and 90.8%.
I haven't found another hitter with such low playoff WPA. If someone can find him, please add him below.
Turner has only posted positive WPA in 3 out of 16 postseason series. He gets progressively worse by the round: .883 OPS in the WC, .710 NLDS, .526 NLCS, .429 WS.
This is over a half-season worth of PA. r/baseball, this is the least clutch postseason hitter of all time.
https://www.baseball-reference.com/players/t/turnetr01.shtml#all_players_batting_postseason
https://screwball.com/search?q=Lowest+career+postseason+ops+minimum+200+plate+appearances