The Padres' pitching staff ERAs seem to represent what many Padres' fans would take away from their early season performance. Cashner has been excellent (2.68 ERA), Ross and Kennedy have been good (3.16 ERA each) and Erlin has struggled (6.35 ERA). However, FIP tells a slightly different story. While Cashner (2.76 FIP) and Kennedy (2.52) have a FIP that represents excellent performance (league avg is 3.79), Erlin surprisingly has a FIP of 2.69 (lower than Ross' pedestrian 3.88).
Erlin's other peripheral stats match up well with Cashner:
Cashner: 0.4=HR/9ip, 2.5=BB/9, 8=K/9, 3.27=K/BB
Erlin: 0.4=HR/9ip, 2.4=BB/9, 7.9=K/9, 3.33=K/BB
One of the biggest statistical differences between Erlin and Cashner has been hits per 9ip. Erlin (10.3 H/9) has given up 2.5 more hits per 9 ip more than Cashner (7.8 H/9). This may be partially explained by a difference in BABIP (Batting Average Balls in Play) - Cashner .282 BABIP - Erlin .342 BABIP.
April numbers can be misleading and I am not ready to lump Erlin and Cashner in the same bucket. However, I am encouraged that Erlin's peripherals indicate that he may see better results if he continues to pitch the way he has in April.