By now, surely you’ve seen the bad news for San Francisco: standout young catcher Buster Posey suffered a left leg injury (assumed to be a broken left ankle and torn ligaments) as a result of a collision with Marlins outfielder Scott Cousins in last night’s game. The injury appears to be season ending, leaving the Giants without one of the best catchers — and players — in the game.
Even though the 24-year-old Posey hadn’t completely hit his stride yet, with a meager .389 slugging percentage, he was still productive for the Giants. His .368 on-base percentage represented a marked improvement over last season’s .351 mark, and his 113 wRC+ ranked fourth among qualified catchers. Throw in his significant defensive contributions — 15 CS against 27 SB, a solid 36% rate — and Posey’s 1.8 WAR ranks only behind Rusell Martin’s 2.0.
According to ZiPS, Posey was primed to get back to last year’s numbers, a .366 wOBA and roughly 4.0 WAR over the latter four months of the season. Replacing that kind of production is nearly impossible; it becomes even harder from the catcher position, as very few players will be available and the internal options are less than impressive. Eli Whiteside will crouch behind the dish for San Francisco today, and the Giants can only hope he can improve on his career .283 wOBA. ZiPS is not confident, projecting a .281 wOBA. Such a mark would place Whiteside marginally above replacement level over 300 or so plate appearances. Thus, it seems fair to say Posey’s injury looks to cost the Giants somewhere between three and four wins without some sort of move for a replacement catcher.
The Giants currently hold a 2.5 game lead on Arizona, a team which will likely regress, and a three game lead on their real competitor, Colorado. According to Baseball Prospectus’s playoff odds, the Giants entered today with an 86.3% chance at the playoffs, including 82.8% odds of winning the NL West. Those odds, however, assume the Giants are a .564 true winning percentage team, or just over a 91-win team. Without Posey, the Giants’ would then be closer to an 86-win true talent team, or a .531 true winning percentage team.
Even with that adjustment, the Giants project as slightly better than Colorado (.525 according to BP) going forward, largely thanks to the tremendous ability of San Francisco’s pitching staff. The Giants will remain favorites by a decent margin, but instead of winning the division 8 out of 9 times, it will be more like 5 or 6. For example, the Cardinals have a .010 expected winning percentage lead on Milwaukee and a 2.5 game lead in the division, and are division winners 66% of the time.
There is still time for the Giants to pick up a worthy replacement for Posey, but given the scarcity at the catcher position, a match may be difficult to find. In the current situation, the Colorado Rockies once again have hope, despite their horrid month of May. Luckily for San Francisco, they built up a head start with Posey. It’s enough of a head start for San Francisco to retain their position as favorites, but chances are the race in the NL West will be tight down the stretch.
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