Alex Gordon singled in the winning run for Kansas City in the bottom of the tenth as the Royals beat the Cardinals 4-3. That drops St. Louis into a first place tie with the Pittsburgh Pirates, both teams at 48-30. The two teams are close defensively, with the Pirates allowing the second lowest runs per game in the NL at 3.46 per game, the Cardinals third at 3.53. St. Louis, however, leads the NL in scoring at 4.97 runs per game, over a run more per game than the Pirates at 3.92 per game. Detailed standings at Baseball Reference show the Cardinals have won three fewer game than expected while the Pirates won five more. The five game swing for the Pirates is the largest of any NL team this year.
You can see why in the sparklines for the two teams. If you look at the Pirates season in run differences, they are winning close games but losing big. The Cardinals are the opposite, pounding teams when they win, but losing close ones.
This strikes me as exactly the kind of situation that would lead to a Pirates swoon later in the year. Great teams win big. That’s what the Cardinals are doing. If the run difference keeps up the rest of the season, St. Louis should win the division handily. I suspect, however, the addition of Jordy Mercer made the Pirates offense much better. (Clint Barmes was a black hole of outs.) I also suspect the Pirates might find a power bat for right field or first base, the last weak links on the team. Pittsburgh has been lucky so far, and it’s up to the front office to make sure that lucky start isn’t squandered by assuming the good fortune will continue.
This argument is only partially correct:
– Teams with strong relief pitching (particularly short relief, like PIT) routinely exceed Pythagorean expectation. So PIT is somewhat less lucky than their run differential indicates.
– PIT has a lot of their bad pitching tied up in pitchers who are not going to effect future wins and losses – pitchers who are clearly not going to pitch any more (e.g., because of injury), or have pitched less than some threshold of innings or have ridiculous ERAs (and are therefore used only in extremely low leverage situations). This eliminates -3.0 WAR of bad PIT pitching (73 runs in 79.1 innings) (if you include MacDonald in this category). If you remove these pitchers from the equation, the remaining pitchers have given up 2.7 RA/9. By comparison, STL ditches only -1.8 WAR (38 runs in 37.1 innings, almost all in the form of Mitchel Boggs), leaving them with 3.2 RA/9. So looking forward (and of course ignoring various possibly unsustainable pitching statistics), we would expect PIT pitching to be substantially better than STL pitching over the rest of the season.