Don't be fooled by Ashcraft's season ERA, he's been on fire his last 11 starts with a 2.39 ERA and held opponents have a .669 OPS against him over that time span. He's gone at least 6.2 IP in his 5 starts too so he's pitching deep into games.
His FIP over that span is in the high 4's though so its possibly he's getting extremely lucky, but 11 starts is a pretty good chunk of the season and his worst start in that span was when he went 7IP giving up 3 ER.