Since 2015, the Giants have had the worst outfield in the major leagues. Over the last four and a half seasons, Giants outfielders have amassed just 8.6 wins above replacement according to FanGraphs. In 51 individual seasons by 33 players, Giants outfielders still couldn’t match one typical Mike Trout season. It’s generally unfair to compare anyone to Mike Trout, but this is a horde of players. They ought to be able to outperform what one player generally does in a year even if that player is one of the best players ever.
But they can’t even outperform a faintly good player. Mitch Haniger has been worth 8.6 wins since 2015, so the typical Giants outfielder has been about as valuable as 1/33 of a Mitch Haniger.
Not all of the Giants outfielders have been bad, but none of them have been good. The best season by a Giants outfielder was Gregor Blanco’s two-win season in 2015. Two wins is about what you expect from a typical, good starter. Behind him was Andrew McCutchen with 1.8 fWAR, and he was traded in August. Knowing this, we need to redefine what a successful season for a Giants outfielder is. It’s unreasonable to expect any to be a typical starter. That would be a 99th percentile outcome. But we can hope for them to be just about average.
Enter Mike Yastrzemski.
Through his first 22 games, this is what Yastrzemski has hit:
.250/.316/.426, .315 wOBA, 96 wRC+
This is what the league is hitting this year:
.250/.321/.429, .318 wOBA, 97 wRC+
That’s as average as you can mathematically get without going over. Turn one of his outs into a single and his slash line jumps up to .264/.329/.441. The average hitter has been worth about 0.7 fWAR per 600 plate appearances. Yastrzemski won’t get enough opportunities to get 600 plate appearances this, but if he hits 0.7 fWAR, he’ll be eighth-most valuable Giants outfielder since 2015. Out of 33 players, he’s already in the top half with 0.1 fWAR. Another tenth of a win, and he’ll break his tie with Giants legend Alejandro De Aza.
It’s completely reasonable to hope that Yastrzemski can do exactly what he’s done so far. All he has to do is be a normal major leaguer, and he’ll be a vast improvement over two-thirds of the players the Giants have tried to stick in the corners since their last championship. It’s not like he’s getting supremely lucky. He’s running a .304 BABIP, and he’s walking and striking out a normal amount of times. His HR/FB percentage of 14.3 is extremely average.
Mike Yastrzemski hasn’t been good so far, but he hasn’t been bad. He’s been perfectly acceptable. For any other team, this wouldn’t be remarkable. Since he’s playing for the Giants, this is incredible.