1. Brendan Donovan
If there were a utility spot for the All-Star Game, similar to the Gold Glove award, I believe Brendan Donovan would surpass the competition and earn a spot on the roster. Although Donovan is listed as an outfielder and demonstrates exceptional defense while batting .282/.374/.416, it's not enough to compete with some of the outfielders who were voted in as reserves or starters.
The player who compares most closely to Donovan but made the All-Star team would be Lourdes Gurriel Jr., who is slashing .268/.319/.495. One factor that overlooks Donovan in a single-position voting system is his versatility around the diamond. I believe this puts him ahead of Gurriel Jr., and it even reflects in the WAR statistic. According to Fangraphs, Donovan has a 0.5 higher WAR than Gurriel Jr.
Another reason Donovan is overlooked is simply because the Cardinals are not performing as well as the Diamondbacks. The Diamondbacks have a record of 50-36, practically the opposite of the Cardinals' record. As a result, Gurriel is receiving more All-Star recognition.