Quote:
Originally Posted by David Watts
Didn't realize Semien's fielding had improved.
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You don't have to
You just have to realize that Semien is a SS and Alonzo is a 1Bman.
And no matter how bad you thought Semien was, if Alonso wasn't **way**
worse, they would have him playing SS.
Here's FGs WAR (broken down) for them both
Alonso 39 batting runs, -1 base running, 0 fielding, -10 positional, 1 league, 20 replacement
Semien 28 batting runs, 1 base running, 6 fielding, 7 positional, 3 league, 22 replacement.
https://www.fangraphs.com/leaders.as...ate=2019-12-31
So, starting with defense, since, it's already been referenced.
Defense is the player's defense relative to the average player at that position, plus the positional adjustment. People largely nonunderstand the positional adjustment. It's what I was getting at with Alonso playing SS. Since the defense measurement compares the player to the average at the position it's necessary to adjust for positions-the average SS is a better defender than the average 1Bman. That's been calculated at about 20 runs over the course of a full season (this may be something that needs to be updated. With more K's and more HR's, defense is becoming less important).
So, so far on the season, the average SS has been worth about 17 more runs than the average 1Bman (7 minus -10).
Then, Alonso has been about equal to the average 1Bman, while Semien has saved 6 runs compared to an average SS.
Semien has been worth (6-0) + (7 minus - 10) 23 more runs than Alonso on defense.
Now, offense.
Alonso, shockingly, I know, has been the better hitter. But, it's probably not as big a gap as one may think.
Their OBPs are pretty close (.362 to .366). With Alonso about a 90 point lead in ISO. When adjusting for park and league, Alonso has been 16% better than a league average hitter and Semien 11% better than a league average hitter. A pretty small gap. Why? Yes, Alonso has 20 more HRs but Semien has 10 more doubles and 5 more triples. Alonso is better, but Semien is close. Semien also has also 60 more PA's which narrow the gap.
Anywho, FG calculates that Alonso's hitting has been worth about 11 more runs than Semien's. Sounds about right, no? 19 more homers, but 15 less doubles and triples.
Another part of offense is baserunning.
Neither guy has been a great base runner. +1 and - 1, basically. But, unsurprisingly, the SS has been a bit better than the 1Bman. Semien leads in steals (10-1). But, also CS (8-0). There's also non-SB baserunning, which isn't separated out.
Again, Semien's base running has been worth about 2 more runs than Alonso's (all the CS are killing him).
Offensively, Semien has been worth 9 less runs than Alonso (11 less batting runs, and 2 more base running runs).
Add that to the Semien's 23 run lead on defense, and Semien still leads by 14 runs.
That's, really, the majority of it.
A few small adjustments more.
First, the adjustment for replacement level.
All the above (hitting, baserunning, defense) are compared to average. That's not a great baseline. Why?
Because below average players still have value. A team with all average players would still win about 81 games a year. Lots of teams don't win 81 games a year.
Also, think about a player who gets called up and sits on the bench. He'd have a value of 0, because he hasn't done anything, good, or bad. Then think about a player who is a bit worse than average but plays all year for the Marlins. Say, Miguel Rojas. Rojas has been worth 1.6 WAR so far this year. Pretend he did that over a full season. If we compared to average he'd be -0.4. It would look like he provided less value than the guy who did nothing. That's just no true. That's why we adjust for replacement level. When we adjust for replacement level, the guy who didn't play would still be at 0. But, Rojas, just below average goes up to 1.6. More realistic.
As I said earlier, Semien played a bit more than Alonso, so he gets a few run advantage over him in replacement level; 22 runs to 20.
Add those 2 runs to his 14 run lead in offense and defense and he's up to 16 runs.
Then there's the league adjustment. This is at attempt to compare between leagues and across seasons. Fangraphs thinks that the AL is a bit tougher than the NL this year, so Semien gets a 2 run bump over Alonso.
Add those 2 runs to Semien's 16 run lead, and he's up to 18 runs.
And that's it.
Just need to convert runs to wins. The easy method is to divide by 10. 18/10 = 1.8. Basically the 2 wins. Why ten runs? Because, over the course of a season, a team that scores 10 more runs than it allows, wins one more game than it loses. A team that scores 20 more runs than it allows wins 2 more games than it loses. And so on.
And, that's why Semien has been worth 2 more wins than Alonso even though Alonso has 20 more home runs.
His defense provides much more value than Alonso's
His doubles and triples and extra PA's close the gap on Alonso's HRs
He runs the bases just a little bit better
He plays in the tougher league
He's played a little bit more.
Simple concepts.
More difficult, but not super difficult math.
A lot of factors to consider.
That's WAR