I've noticed some people disparaging the notion of a pitcher putting up league average numbers having much value. After all, the reasoning goes, league average includes all the bad teams whereas the average rotation to make the playoffs would be more telling (because no mediocre teams make the playoffs). Snark aside, there's a certain logic in that line of thinking. Making the playoffs with a below average rotation is possible (see: 2007 Phillies), but rare.
With that in mind, I decided to crunch the numbers and find out the rotation numbers of playoff teams over the past five seasons. Treating all four teams each year as one giant staff starting approximately 648 games, I then figured out the FIP and ERA for each rotation spot. Below are the results compared to the relevant league average for each season. The numbers (#1, #2, etc.) correspond to each spot in the rotation.
|2003||AL Playoff Teams||4.10||3.18||3.77||4.23||4.43||5.15|
|2004||AL Playoff Teams||4.38||3.42||3.93||4.34||4.95||5.55|
|2005||AL Playoff Teams||4.33||3.60||4.05||4.30||4.56||5.43|
|2006||AL Playoff Teams||4.49||3.31||4.19||4.47||4.81||6.03|
|2007||AL Playoff Teams||4.18||3.22||3.80||4.12||4.50||5.67|
|Last 5||AL Playoff Teams||4.29||3.31||3.96||4.28||4.61||5.63|
Only in one spot in on year did the league out-perform the playoff teams. In 2006, the league average #2 starter had an FIP of 4.18 compared to the playoff teams' 4.19. Otherwise the playoff squads handily outpaced the rest of the league. The average playoff team's starter FIP was between 92.6% that of the league's. Note, however, that a league average starter (by FIP) still makes a good #4 pitcher for a playoff team based on the last five seasons.
|2003||AL Playoff Teams||4.15||2.66||3.66||4.30||4.61||6.04|
|2004||AL Playoff Teams||4.47||3.22||4.03||4.58||4.99||6.27|
|2005||AL Playoff Teams||4.15||3.21||3.59||4.00||4.52||6.17|
|2006||AL Playoff Teams||4.38||3.16||3.80||4.19||4.81||6.58|
|2007||AL Playoff Teams||4.29||3.07||3.70||4.26||4.73||6.27|
|Last 5||AL Playoff Teams||4.29||3.02||3.77||4.26||4.74||6.29|
Again the playoff teams sink to league average in only one spot: #1 pitchers on playoff teams in 2005 were league average. Of course, when the rest of your rotation outpitches everyone else, you can afford that. The average playoff team ERA was 91.8% that of the league, or about the same as the difference in FIP. Not surprisingly, then, a league average pitcher slots in at #4 on a playoff team using ERA again.
So now that it turns out a league average starter is generally a good #4 starter on a playoff team in the American League, let's turn to the senior circuit. Pitching in the NL is considered to have a positive effect on a pitcher's statistics since opposing pitchers bat for themselves and the NL FIP has been below that of the AL in four of the past five seasons (2007 is the exception). Similarly, the NL ERA was higher than the AL ERA only in 2007. Perhaps, then, this skews the importance of league average starters to NL playoff teams.
|2003||NL Playoff Teams||4.13||3.08||3.82||4.14||4.55||5.42|
|2004||NL Playoff Teams||4.50||3.38||4.08||4.47||4.92||6.17|
|2005||NL Playoff Teams||4.20||3.11||3.68||4.36||4.72||5.48|
|2006||NL Playoff Teams||4.65||3.56||4.16||4.72||5.12||5.97|
|2007||NL Playoff Teams||4.66||3.64||4.34||4.70||5.01||5.90|
|Last 5||NL Playoff Teams||4.42||3.28||4.03||4.46||4.89||5.83|
The past two seasons have been interesting in the National League. The general mediocrity of the starting staffs of the Cardinals and Mets in 2006 contributed the most to the #3 and #4 spots on playoff teams doing worse than league average (the Cardinals #3 starters had a 5.31 FIP!). Of course, each of those teams had better than average results from their fifth starters which no doubt helped them win enough games to get into the playoffs.
Last season is a different story. The Rockies (4.67) and Phillies (4.86) both had below average starting staffs overall. The Diamondbacks (4.58) and Cubs (4.54) were above average, but not by much. Cumulatively, this means the average playoff rotation was worse than league average overall. Only in the fourth and fifth starter spots did the playoff teams manage to outperform the league. There might be a moral in there (depth! depth! depth!). In any event, the National League in the past two seasons has shown that if you can run a half-decent staff out there and mash the ball, you've got a real shot.
The average NL playoff team rotation over the past five years put up an FIP that was 96.8% that of the league. Again, a league average starter slots in as a #4 overall, but in the past two seasons, playoff teams could use such a pitcher as a #3 guy. Maybe ERA will clear up the picture: perhaps these FIP-challenged teams were ERA-lucky.
|2003||NL Playoff Teams||3.90||2.75||3.45||3.90||4.24||5.66|
|2004||NL Playoff Teams||4.12||3.03||3.61||4.04||4.35||6.76|
|2005||NL Playoff Teams||3.79||2.42||3.09||3.78||4.45||5.66|
|2006||NL Playoff Teams||4.46||3.31||3.74||4.21||4.90||6.17|
|2007||NL Playoff Teams||4.47||3.43||4.00||4.30||4.78||6.51|
|Last 5||NL Playoff Teams||4.14||2.86||3.63||4.07||4.54||6.29|
ERA makes recent playoff teams look a little better. Only the #1 and #2 (barely) starters last season were substandard, while only 2006 aces were below average. As long as most of your rotation outperforms their equivalents around the league, you can deal with a slightly below average top dog. The #1 pitchers in 2004 didn't get lucky in this table either, still finishing a little below the league average.
The playoff team ERA is 92.7% that of the league average over the past five seasons. That's close to the American League's numbers for FIP and ERA. League average starters are, yet again, good #4 starters on playoff teams.
I can see some people complaining that numbers like FIP and ERA don't get you into the playoffs: it's wins that count! With that in mind, I averaged the wins by each starting staff in each league in each season. In the American League, playoff teams could expect about 70 wins from their rotation each year. In the National League, that number drops to 65 wins. Either way, I think the moral of the story is it takes good defense combined with great offense to overcome a league average pitching staff and make the playoffs, but it's certainly possible.