STAT LINE .251 / .333 / .307 (225 PA), 1 HR, 23 RBI, 20 BB, 69 K, 0.0 fWAR

There’s only one word to describe the concept of Wins Above Replacement: esoteric. What is WAR good for? Measuring value, of course, but try as we might, value always appears to be in the eye of the beholder. Still, back to the first point. Sabrmetrics has always defined “Replacement” as a 4-A minor leaguer or minor league free agent. Someone who earns the minimum minor league salary. But what does that mean?

One thing to keep in mind for this definition is that scouts and management decide who’s replacement through scouting reports and the purchasing of player rights. That’s the minimum threshold, and it’s a good one, because it establishes the pool of players and from that pool, the various tiers are established. Now, to the larger point: Austin Slater’s 0.0 fWAR in 2018 means that he zero runs above or below replacement. He was exactly replacement-level. A major league average player.

Fangraphs’ fWAR takes into account defense and base running along with offense and positional adjustment. Slater measured below average on offense (-4.5 runs, or above half a win) and defense (-2.3 runs), but 0.8 with Base Running. It also factors in the league performance. You can read about how they calculate it specifically here. Taken together, there was nothing remarkable about what he did, but nothing terrible, either.

Role on the 2018 team

At the beginning of August, I singled him out as an ambassador for The Giants Way of hitting. It was somewhat tongue in cheek, but, at the same time, you can see the organization’s intentions behind his particular swing.

When he hits the ball, he hits it hard. And if you go through the flyball (FB/LD) and groundball (GB) velocity split, it gets even more obvious in terms of what Slater does: that 91.5 mph average exit velocity on fly balls is pedestrian (257th in MLB), but the 89.7 mph on groundballs is 38th. Slater’s swing — indeed, his entire game — is centered around making hard contact. The scouting reports on him suggest this is his best destiny.

The Giants want players who make contact, preferably hard contact. Thing is, for all that hard contact, Slater’s .307 slugging percentage was the 22nd-worst in all of Major League Baseball (minimum 200 plate appearances) and his 30.7% strikeout rate was 28th-worst (just ahead of Aaron Judge!). He had as many extra base hits as Chase d’Arnaud (8), Mac Williamson, and Austin Jackson and only two more than Kelby Tomlinson.

His lack of power compelled Kenny to write this post just ten days after mine:

Slater’s average exit velocity is 88.9 which is the same as Juan Soto and George Springer. But Soto and Springer have ISO’s of .247 and .186 respectively. Slater’s is a palty .039. Exit velocity doesn’t always translate to power, however. In Tuesday’s game, Manny Machado hit a ball at 108 MPH but it was on the ground right at Evan Longoria. Justin Turner nearly hit a dinger at 95 MPH. Hitting the ball hard doesn’t make a difference if you can’t hit the ball in the air.

He played basically every day beginning in August, and the final two months of the season did very little to cement the idea that he should be considered for a starting role in 2019. He slashed .229 / .280 / .286 over the final two months (47 games, 150 plate appearances), and if Win Probability Added has much meaning to you, then you should note that he amassed a -1.411, meaning everything he did on offense for two months did not improve the Giants’ chances of winning a baseball game.

Role on the 2019 team

Here’s hoping Slater considers 2018 a valuable learning experience. He has nowhere to go but up. Also, the Giants’ outfield depth chart looks like this right now:

I don’t think his performance earned a trip back to Triple-A to figure things out and on a rebuilding/reloading/reimagining team, replacement level players are good to have around.

Slater’s 75.4% contact rate was only 8th-best on the team, but some of that is attributable to his really poor 66% swing rate at pitches in the strike zone. That’s not to say he was wild outside the strike zone. That was only a 31.8% swing rate, 6th-best on the team. He needs to be more aggressive in the strike zone by simply swinging at strikes. When he did swing at strikes, he had a contact rate of 85.2%, 5th-best on the team.

Figure Slater to be the fifth outfielder with a chance to be the fourth outfielder, along with the possibility of some position flexibility on the infield.

Final Grade: C+

If you ever look at a WAR leaderboard, now you can say, “Oh, Mookie Betts is 10.4 wins better than Austin Slater.”