Do teams do this?
I think it was wise for the Tigers to add a RHH OF. I would have preferred CF, but that's tough to come by in free agency, plus they already had Vierling on the roster, so maybe CF wasn't that big of a deal.
I'm fine with Canha. I don't recall the exactly, but I think he had a team option that Milwaukee wasn't going to pick up. I like that it's only a one year deal because I want to see Malloy promoted eventually. Perhaps among OF/DH they can roll out Greene, Carpenter, Meadows, and Malloy. There's still a need for RHH OF, but I think Vierling has improved his stock enough to count him in next season. And Perez has shown well so far also. So, I think they could reasonably have internal options for next season with a decent floor.
I think if they were going to really impact the lineup, 3B would have been the target over last offseason, and still could be this season (maybe). And who knows, maybe Torkelson flames out and 1B becomes a concern, too.
But, going back to Hernandez/Canha, they got themselves what they needed with Canha. I think the one year was better than multiple years. And we don't know if they reached out to Hernandez (or anyone else) or not.