The right-hander is 1-4 after five starts, despite a 2.61 ERA. The Padres have scored 15 runs in his five starts, but only nine when he was still in the game. And in Cashner's last two starts, they have scored just two runs.
Cashner on Wednesday became just the fourth Major Leaguer in the past 30 seasons with four losses in April and a sub-2.70 ERA.
Meanwhile, the defense has committed six errors and two passed balls while Cashner has been pitching this season. That has led to eight unearned runs charged to Cashner, who has allowed a total of 17 runs in 32 innings.
Errors or passed balls have played a role in three of his four losses.
Cashner set a Major League record Wednesday afternoon, when he extended his record of not allowing more than two earned runs at home to 21 straight starts. The Dodgers' Orel Hershiser and Miami's Jose Fernandez both went 20 straight starts allowing no more than two earned runs in a game, although Fernandez's streak is also active.
But Cashner is 6-9 during the streak despite a 1.50 ERA (24 earned runs allowed in 144 1/3 innings). He is 0-3 at Petco Park this season, despite a 1.80 ERA in three starts covering 20 innings.
Dating back to Aug. 14, 2013, Cashner is 8-14 despite a 2.23 ERA -- which is the third-best ERA among qualifying pitchers over that time to Clayton Kershaw's 1.97 and Johnny Cueto's 2.16. Over his 206 innings during the run, Cashner has 174 strikeouts with only 44 walks.
Last season, Cashner was 5-7 with a 2.55 ERA, becoming the first starting pitcher in Padres history (and the first in the Major Leagues since the Cardinals' Joe Magrane in 1988) to post an ERA of 2.55 or lower while having a winning percentage of .417 or lower.
From the scorebook
• Right fielder Matt Kemp, who was 1-for-4 with a double and two RBIs Wednesday, hit .326 in April (30-for-92) with seven doubles, two triples and a homer, with 16 RBIs and 16 runs. Kemp is a career .318 hitter in April (230-for-723), which is the fourth-highest mark among active players. He was 9-for-20 (.450) against left-handed pitchers this month, with four doubles and eight RBIs. He is a career .333 hitter (370-for-1,110) against left-handed pitchers, the third-best mark among active players.
• The 21 runs scored by center fielder Wil Myers in April is the third most for the month in Padres history. Outfielder Al Martin holds the Padres' record for runs scored in April, with 25 in 2000. Third baseman Ken Caminiti is second, with 23 runs scored in 1996. Myers is hitting .316 (25-for-79) in his last 19 games with four homers, 19 runs and 14 RBIs.
• First baseman Yonder Alonso is 1-for-18 in his last five games. Left fielder Justin Upton has one hit, his sixth homer, in his last 15 at-bats. Third baseman Will Middlebrooks is 2-for-15 since his eight-game hitting streak ended. Second baseman Jedd Gyorko is in an 0-for-11 slide.
• The Padres have a total of 24 errors (19) and passed balls (five), the highest combined total in the Major Leagues. The Padres have allowed 14 unearned runs in 23 games, tied for the second-highest total in the Major Leagues.
"I think the defense has been a little bit spotty, especially in the infield," said Padres manager Bud Black. "We have to clean it up a little bit."