With the Rays sitting at 32-13, obviously the Rays pitchers have been accruing wins – 32 of them, in fact. The Rays also have been the benefactors of both good defense and good luck. Entering tonight’s game against Boston, Rays pitchers had allowed only a 2.87 ERA against a 3.78 FIP and a 4.06 xFIP. They’ve benefited from a league best .272 BABIP. much of which can be attributed to defensive wizards such as B.J. Upton, Evan Longoria, Carl Crawford, and Jason Bartlett – and a HR/FB rate of only 8.6%, about 1% below the league average.
Still, even though it might not hold up for the whole season, there’s no arguing with the results so far. The Rays pitching staff has been by far the best in the MLB in terms of win probability, both in terms of straight WPA and context adjusted WPA/LI. The Rays 8.31 pitcher WPA leads the second place Padres by over 2.5 wins and the Twins, the second best AL team, by over four wins. Although they’ve performed over two wins worse by WPA/LI at 5.98, that’s still easily best in the majors. The Twins, again, are the next best team, and they come in at only 3.93.
It’s hard for a team to win 71.1% of their games for a 45 game stretch, even with good luck. It’s even harder for a team to actually play at the level of a 115 win team for 45 games, which, according to Pythagorean record, the Rays have. The pitching staff and defense are, naturally, the biggest part of that. The Rays 144 runs allowed are the lowest in the AL by a whopping 37 runs, despite the run prevention techniques employed by some richer teams this offseason.
The scariest part of all this is that the Rays hitters haven’t joined the party yet. Their .337 wOBA is certainly respectable. It works out to about 15 runs above average, right around what their +1.69 WPA suggests. If the hitters were merely producing at an average level, WPA suggests that the Rays would still be about 16 games over .500, at a 31-14 or 30-15 mark. That would still the best record in baseball by four or five games.
So even though Rays pitchers are potentially due for negative regression, depending on how much of their low BABIP is defense related and how much is luck related, the offense may be due for positive regression. Carlos Pena, B.J. Upton, and Jason Bartlett are all yet to find their stroke, and the loss of Kelly Shoppach to injury has damaged the Rays at catcher, despite the recent surge from John Jaso. The Rays have played about as well as possible for 45 games, and there’s no reason to expect them to stop now.