Keep: Brendan Donovan
Brendan Donovan is no longer just a scrappy player who knows how to win. He still is that, but it's also time to respect him a legit difference maker for the Cardinals. Here are his numbers since 5/23.
.321/.410/.522, 8 HR, 23 RBI, 158 wRC+, 2.0 WAR
That is tied for the 13th-best WAR since that date, and he has the 9th-best wRC+ in baseball. Pair that with the ability to play six positions, and you have yourself an extremely valuable ball player.
Donovan has also been the Cardinals' most "clutch hitter" so far this year, proving that he comes through when the club needs him the most. He's under team control through the 2028 season, and it's no wonder why teams are so interested in hiim.
Sure, if some club comes in with an offer the Cardinals cannot refuse, he's techinically not untouchable. But other than that, the Cardinals have plenty of other assets worth shopping around.