Miley pitched his best game of the season Tuesday in Pittsburgh, but couldn't earn the win when closer Addison Reed blew the save.
Miley allowed two hits in eight shutout innings, as the D-backs entered the ninth inning leading 2-0.
Instead of finishing his shutout, Miley surrendered back-to-back hits to lead off the ninth. In came Reed, who gave up a game-tying double, which was nearly caught, and the walk-off single.
"He battled and gave it everything he had," D-backs general manager Kevin Towers said on the Doug and Wolf show on Arizona Sports 98.7 FM. "You even look at the couple hits in the ninth inning, they weren't hit hard, they just happened to find spots."
Miley is 3-6 in 2014 and is carrying a career-worst 4.61 ERA following a two-season stretch when he was 26-21 with a 3.44 ERA. While Miley has had other solid outings this season, none were quite as dominant as Tuesday night's gem.
"I thought he had good tempo right from the beginning of the game," Towers said. "He attacked the zone. He was keeping the ball out of the middle part of the plate. He was changing speeds. I thought he had an extra gear with fastball when he needed it last night. He was hitting all different quadrants."
Miley fanned 10 hitters without allowing a walk for only the second time in his career. Towers thinks the lefty may be able to string together better starts with the improved strikeout to walk ratio.
"When the walks are down (and) the strikeouts are up, those are good indicators that a guy's starting to turn it around," Towers said.