The nice part about a Juan Yepez deal is that the Cardinals are not limited to dealing with contending teams. The Tigers could be interested in bringing in Yepez to be a part of their lineup long-term.
Last year, Yepez got to hangout and learn from Albert Pujols on his farewell tour. He could do the same with future Hall of Famer Miguel Cabrera while finishing playing time at DH, 1B, and 3B on a daily basis.
The Tigers are another team with a lot of young arms, many of whom are former top prospects who haven't quite figured things out. A few of those arms could pique the Cardinals' interest and get a deal done. If I were St. Louis though, I would package Yepez with multiple other young pieces to go after injured ace Tarik Skubal.
Skubal was 7-8 with a 3.52 ERA in 117.2 in his age-25 season before suffering a flexor tendon injury. Skubal should be back from his rehab mid-way through this summer and may be a nice "ace in the hole" that they can acquire to upgrade their rotation while owning dipping from depth pieces and prospects.