A lot is riding on the health of A’s closer Sean Doolittle. The big-bearded southpaw has been a monster all season long, but was placed on the 15-day DL this week with a strained right intercostal muscle. Initial reports say he’ll likely miss the rest of the regular season but should be back in time for the playoffs.

Braves closer Craig Kimbrel carries some serious late-inning heat, averaging 97 mph on his fastball. He leads all qualified closers in strikeout rate at 40.2%, closely followed by Kenley Jansen (39.0%) and Doolittle (38.7%). Jansen has been on an absolute tear the last two months, and Greg Holland has preserved his fair share of wins for the Royals.

But really, its Doolittle’s minuscule 2.4% walk rate that is leaps and bounds above everyone else. He’s got 80 strikeouts to only five free passes this season, leaving him with a 16.00 strikeout-to-walk ratio, six points better than any other reliever in the league. That’s the best mark since former A’s pitcher Dennis Eckersley posted an 18.25 rate in 1989 and 18.33 in 1990. The ability to punch guys out and make batter’s earn their bases the hard way is a road to success paved in gold, especially in the heat of the postseason. But the lagging question remains, will Doolittle be back to full strength?