He was much more pleased with the Astros' work at the plate on Thursday night.
Carlos Lee doubled and drove in a season-high-tying four runs, pinch-hitter Matt Downs knocked in three more and the Astros beat Colorado 9-6, extending the Rockies' losing streak to a season-high eight games.
Lee has heated up since the All-Star break to reach 90 RBIs this season after having just 48 in the 88 games before the break.
"That's a lot of runs compared to what I was three months ago," Lee said. "That's something I take a lot of pride in in my career is driving in runs."
Mills has been impressed with Lee's improvement in the second half.
"You can always look back and last year he was off to a slow start as well," Mills said. "And what he's been able to do and the four RBIs tonight were huge to get to 90. What he's done the last two, three months has been pretty good."
Houston starter Henry Sosa (3-5) yielded a season-high nine hits but allowed just three runs in 6 1/3 innings to end a three-game losing streak.
Wilin Rosario doubled and hit a three-run homer in the eighth to cut Houston's lead to 8-6 and Kevin Kouzmanoff had a solo shot in the seventh. Rosario has three homers and seven RBIs in the first 12 games of his career.
Rockies starter Alex White (2-3), acquired in the Ubaldo Jimenez trade with Cleveland, allowed six hits and five runs with six strikeouts in 4 2/3 innings. He hit two batters and threw two wild pitches.
"The additional base runners we gave them tonight with them not even having to go up and hit the ball, that kind of stuff is going to get you beat," Rockies manager Jim Tracy said.
Sosa doubled to start the Astros' third before White plunked Jose Altuve with one out. Both players advanced a base on a wild pitch by White before he hit J.D. Martinez with a pitch to load the bases.
Lee's bases-clearing double, which landed on the top of Tal's Hill in center field, gave Houston a 4-2 lead.
Jordan Schafer and Altuve hit consecutive singles in the fifth inning and Schafer advanced to third on a wild pitch by White with one out. Schafer scored on a sacrifice fly by Lee to push the lead to 5-2.
"I felt good tonight (but) I put myself in some bad spots and paid for it," White said.
Houston closer Mark Melancon pitched a perfect ninth for his 20th save.
Kouzmanoff had a solo homer that landed in the Crawford Boxes in left field and got Colorado within 5-3 with no outs in the seventh inning. Rosario followed with a double before Sosa was replaced by Fernando Rodriguez with one out.
Eric Young singled before stealing second base. Dexter Fowler reached on a fielder's choice when Chris Johnson threw home to get Rosario out. Rodriguez walked Jordan Pacheco to load the bases, but escaped the jam by retiring Tulowitzki to end the inning.
Houston tacked on three more runs with a second bases-clearing double by Downs in the seventh inning. The hit gave Downs 15 pinch-hit RBIs this season, which leads the majors and is the second most in a season in franchise history.
Downs said the key to his pinch-hitting success is simply keeping his head in the game when he's on the bench.
"It's just one of those things where you have to pay attention during the game, stay in the game and stay focused," Downs said. "You can't be underneath watching TV and joking around and stuff. You have to stay in the game the whole time and watch how they're pitching guys and watch what they're doing."
Tracy was disappointed that his team allowed the hit to Downs.
"The pinch-hit double off the bench completely changed the complexion of the game," Tracy said.
Tulowitzki and Seth Smith hit consecutive singles to start the second inning. Tulowitzki scored when Kouzmanoff grounded into a force out to make it 1-0.
The Rockies got back to back one-out singles by Young and Fowler in the third inning and Young reached third on Fowler's hit. Young put Colorado back on top when he scored on a wild pitch by Sosa. Fowler went to third on the play on an error by catcher J.R. Towles, but Sosa retired the next two batters to limit the damage.
Houston added a run on a sacrifice fly by Schafer in the eighth inning. By that point only a few fans, from a crowd that was thin to begin with, remained to cheer the worst team in baseball.
Houston RHP Bud Norris, who left his last start in the fourth inning because of shoulder soreness, was diagnosed with right biceps tendinitis on Thursday and won't his scheduled start on Sunday. He will be replaced by RHP Lucas Harrell. ... Rockies manager Jim Tracy said he doesn't plan to play Todd Helton again this season because of his sore back. Tracy said that Helton is OK, but that they don't want to do anything to jeopardize his health for next season. ... The Astros announced plans to celebrate the 50th season of the franchise in 2012 on Thursday. The Astros will wear a 50th anniversary patch on their uniforms and will don throwback jerseys from different eras during each Friday home game. ... RHP Brett Myers will pitch for Houston against Colorado lefty Drew Pomeranz in the second game of the four-game series on Friday. Myers is 3-0 with a 1.19 ERA in his last four starts. Pomeranz, a rookie who also came to Colorado in the Jimenez trade, will make his first career road start after allowing two runs and four hits in his last outing.