In the regular season, few pitchers were tougher against right-handed hitters than Lynn. Among starting pitchers, no one was -- Lynn's 1.99 FIP was easily tops in the majors among starters. James Shields was second best at 2.65. Lynn wasn't nearly as good against lefties, as his 5.30 FIP can attest. But in the postseason, Lynn will be deployed in relief and, just like last year, could do significant damage.
On the other side of the coin, we have Zimmerman, who has bashed with authority since receiving a cortisone shot at the end of June. The Nats' 3-hole hitter generally is surrounded by two lefties, with Bryce Harper hitting in front of him and Adam LaRoche behind him. It's not generally a great idea to burn a pitcher who could throw multiple innings on one hitter, but if you're going to make an exception for such a move in a high leverage situation, this is it.