This season, the 30-year-old Axford has pitched to a 4.45 ERA, 1.56 WHIP and 2.35 K/BB ratio in 54 2/3 innings. He put up similar numbers in 2012, but in 2011 Axford, then the Brewers' closer, finished ninth in the NL Cy Young balloting.
Axford still misses bats, but his lack of control and occasional proneness to the home run have been problems. On the upside, he's shown fairly level platoon splits over the course of his career.
"John has been a big contributor to the Brewers, and we do not go to the playoffs in 2011 without his outstanding performance," Brewers GM Dou Melvin said in a statement. "He and his wife, Nicole, will also be missed as contributors to the Milwaukee community."