Playing quarterback in the NFL is the top job in American sports, so a lot of effort in recent years has been put into quantifying performances. Pretty much just yards per pass attempt (YPA) distinguishes the wheat from the chaff, but the NFL has had a synthetic system for decades using YPA, completion percentage, touchdowns, and interceptions.

In 2011 ESPN introduced QBR, a proprietary system where they go back through game video and grade each play and add it all up in a black box formula. For example, for the last decade, Peyton Manning seldom gets sacked so he’s even better than his passing numbers suggest. On the other hand, he can’t run, so that has to be taken into account, too. (Here’s an article explaining QBR.)

For example, everybody who watches a lot of football (i.e., not me has been saying Andrew Luck of Stanford is a top tier quarterback almost since he entered the NFL). But his traditional passing statistics weren’t that great until this season, his third. It turns out, though, that he lost quite a few yards off his passing totals in his first couple of seasons due to pass interference penalties (e.g., to prevent a touchdown the defender tackles the receiver before the pass arrives). This year his traditional passing numbers look excellent, but he’s fumbling more and getting fewer pass interference calls, so his overall performance is about the same as last year.

I haven’t checked into this, but I wouldn’t be surprised if this more sophisticated statistic just smooths out year-to-year variation. The top ten guys so far this year in QBR are Aaron Rodgers, Peyton Manning, Tony Romo, Tom Brady, Philip Rivers, Drew Brees, Ben Roethlisberger, Andrew Luck, Joe Flacco, and Eli Manning, names you’ve probably are familiar with.

Football may rank with soccer as a “You can observe a lot just by watching” sport, where statisticians are still trying less to uncover new knowledge than to catch up with what coaches know just from watching a lot of videotape.

Back in 2003 Rush Limbaugh got fired from being a color commentator on Monday Night Football for pointing out that the media had been pushing hard for more black quarterbacks for decades. So Rush got fired because everybody knows that the only reason blacks don’t make up 75% of NFL starting quarterbacks is discrimination and the burdens of history.

So I like to check in on how black quarterbacks are doing. This QBR rating counts their running contributions, so it’s the best measure yet.

Here are black QBs (treating Colin Kaepernick as black) who ranked in the top 20 for each year as far back as QBR has been calculated. I counted the top 20 in a 32 team league since it’s pretty safe to assume that if you rank in the top 20 you deserve to start, whereas if you are, say, 29th, then there’s probably a benchwarmer another team that deserves your job.

• 2014: 2 (Russell Wilson 14, Colin Kaepernick 16)
• 2013: 3 (Colin Kaepernick 6, Russell Wilson 12, Cam Newton 13)
• 2012: 4 (Robert Griffin 5, Russell Wilson 6, Cam Newton 14, Josh Freeman 15)
• 2011: 2 (Michael Vick 7, Cam Newton 15)
• 2010: 3 (Michael Vick 5, Josh Freeman 6, David Garrard 13)
• 2009: 3 (Vince Young 7, Donovan McNabb 13, David Garrard 19)
• 2008: 3 (David Garrard 16, Jason Campbell 17, Donovan McNabb 18)
• 2007: 4 (David Garrard 3, Jason Campbell 15, Donovan McNabb 16, Tarvaris Jackson 19)
• 2006: 4 (Steve McNair 6, Donovan McNabb 7, Vince Young 11, Michael Vick 15)

So, there’s no particular trend going on. There was a time in the past when there were few black quarterbacks, but that was a long time ago. In Los Angeles, it was a really long time ago. USC had a black quarterback in 1969 and the Rams dumped the 1972 NFL MVP John Hadl in mid-season 1973 for James Harris.

This recent data reflect the general pattern that in a lot of areas where there was past discrimination, we seem to have reached a stable state some time ago.