A blog that pretends to undertake serious studies of baseball, provide critical commentary, and rant about when to pitch Mariano Rivera.
Tuesday, January 26, 2010
What caused the "Steroid" Era?
That's the question that J.C. Bradbury asks in this post. If you've followed my thoughts on steroids here, you'll be familiar with his answer. Nonetheless, his post is worth reading as a concise, focused, and effective primer on what happened and why in the 1990s.
Is there really so little evidence for the ball changing? Bradbury mentions broad speculation to this effect. Isn't such information, if not widely, at least somewhat available?
I would find it really funny if MLB changed up the bats and balls and a bunch of other factors in the game, causing home runs to skyrocket, and then had to endure years of allegations that the game has been "tainted" and "just isn't what it used to be" because of, supposedly, steroid usage.
Actually, Bradbury mentions ball changes so casually in part because I think that it's so well known. I'm pretty sure I've linked to studies on this in the past. There's a lot of evidence for it.
ARP measures the amount of runs that a relief pitcher prevented from scoring above what an average relief pitcher would have prevented. ARP is adjusted for the situation in which the pitcher was used.
ISO Isolated Power
ISO is the ratio of extra bases that a player has accumulated to the number of at bats he has received. ISO is essentially a player's SLG minus his batting average. This has the effect of giving a player credit only for extra base hits. ISO is not a useful measure of player value on its own, but is a very effective measure of a player's extra base ability.
OBP On Base Percentage
OBP is the ratio of the number of times a player reached base safely to the number of opportunities he had to reach base. It effectively measures a player's skill at not making outs. Since outs are a teams most precious commodity, OBP measures perhaps the most valuable and fundamental skill a player can have.
OPS On Base Plus Slugging Percentage
OPS is a crude metric that simply sums a player's on base and slugging percentages. It is probably the most popular non-traditional measure of overall batting performance due to its simplicity. However, it has drawn criticism from performance analysts for its inaccuracy relative to other advanced metrics and because it works by adding two numbers with different denominators together to produce a conceptually meaningless quantity. It is best used as a quick and dirty estimator of batting prowess.
SLG Slugging Percentage
SLG is the ratio of total bases that a player has accumulated to the number of at bats he has received. It is essentially a weighted batting average that gives a player more credit for extra base hits.
UZR Ultimate Zone Rating
UZR is a defensive metric that uses play-by-play data to determine how good a player's defense is. On Fangraphs, it is denominated in runs saved above average.
VORP measures the amount of runs that a player contributed above what a "replacement player" at the same position would produce. VORP considers only offensive contributions.
WARP Wins Above Replacement Player
WARP measures the amount of wins that a player contributed above what a "replacement player" at the same position would produce. WARP considers both offensive and defensive contributions.
WXRL Win Expectancy added above Replacement adjusted for Lineup
WXRL measures the amount of wins that a relief pitcher contributed above what a "replacement player" would produce. WXRL differs from WARP because it is adjusted for both the game situation in which the pitcher was used and the hitters that the pitcher faced.
2 comments:
Is there really so little evidence for the ball changing? Bradbury mentions broad speculation to this effect. Isn't such information, if not widely, at least somewhat available?
I would find it really funny if MLB changed up the bats and balls and a bunch of other factors in the game, causing home runs to skyrocket, and then had to endure years of allegations that the game has been "tainted" and "just isn't what it used to be" because of, supposedly, steroid usage.
Actually, Bradbury mentions ball changes so casually in part because I think that it's so well known. I'm pretty sure I've linked to studies on this in the past. There's a lot of evidence for it.
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