DENVER (AP) - Drew Pomeranz struggled once again, begging the question of how much longer the Colorado Rockies will keep the young left-hander in their rotation.
Pomeranz (0-4) was knocked out in the fifth inning of the Rockies' 3-1 loss to the Miami Marlins on Monday night. He gave up five hits, four walks and three runs in 4 1-3 innings. In his four starts with the Rockies, the 24-year-old Pomeranz has an 8.10 ERA and has thrown a staggering 353 pitches - an average of 21.2 per inning - in 16 2-3 innings with 18 walks and 13 strikeouts.
``It's pretty obvious what I need to get better at,'' Pomeranz said. ``It's just walking guys and being in better counts.''
Tom Koehler tied his career-high with seven strikeouts and tossed seven strong innings. Ed Lucas homered and the Marlins scored for the first time in four games while winning the opener of a four-game series.
Giancarlo Stanton reached base three times and Steve Cishek notched his 18th save for Miami, which snapped a four-game losing streak.
Troy Tulowitzki hit his 17th home run and DJ LeMahieu had three hits for the Rockies, who are 2-2 in a key 10-game homestand.
The Marlins' scoring drought reached a franchise-record 37 innings after a three-game sweep at Milwaukee over the weekend. They had not scored since Derek Dietrich's two-run homer in the fourth inning of a loss to Washington on July 14.
They failed to score the last six innings of that game before being shut out in three straight games for the second time in franchise history.
The Marlins ended their frustration right away against Colorado. Lucas reached on a one-out single in the first and scored on Stanton's double to right. Stanton scored on a sacrifice fly to make it 2-0.
Lucas gave Miami a 3-0 lead when he crushed Pomeranz's 89 mph fastball down the left-field line to lead off the third.
Pomeranz, the centerpiece of the Ubaldo Jimenez trade with Cleveland two years ago, began this season in Triple-A before being called up June 28. He had an 8.76 ERA in three starts and was sent to Double-A Tulsa to make one start over the All-Star break before being recalled Monday to start against the Marlins.
``He struggled for most of the night, particularly early,'' Rockies manager Walt Weiss said. ``But he held it together and got out of there with a chance to still win the game. But he struggled, no doubt about it.''
The Rockies are 48-52 but in third place and just four games behind in the mediocre NL West. They have three dependable starters in Jorge De La Rosa, Jhoulys Chacin and Tyler Chatwood, and have hopes for Juan Nicasio, who has made two strong starts. But Pomeranz remains a weak link in their rotation.
``We've got to have quality starts and know Drew is capable of doing it.'' Weiss said. ``We just got to get him right.''
Koehler (2-5) looked sharp in his first start since July 2. His only blemish was Tulowitzki's homer to lead off the fourth that made it 3-1.
Michael Cuddyer followed with a double, but Koehler struck out Todd Helton and retired Wilin Rosario and Nolan Arenado to strand Cuddyer at third.
Koehler allowed one run on eight hits and didn't walk a batter in seven innings. It was the fourth time in 11 starts he has pitched at least seven innings.
Pomeranz has not gone more than 4 1-3 innings in any of his four starts.
``His command needs to gets better,'' Tulowitzki said. ``I think he'll be the first one to tell you that. He falls behind a lot, gets in bad counts. He needs to go back to work and get better. Lot of potential, but sometimes that's not what makes a good player or a pitcher at this level. It's the work you put in. It's the time you spend trying to get better. Potential only gets you so far.''
NOTES: The Rockies optioned INF Josh Rutledge to Triple-A to make room for Pomeranz on the roster. ... Marlins starters have allowed three or fewer runs in 26 of the last 30 games. ... The Rockies will send RHP Jhoulys Chacin (9-4, 3.50 ERA) to the mound against Miami's Jose Fernandez (5-5. 2.75) in the second game of the series Tuesday.