Joint responsibility from Allen and Loomis.
Allen never saw Baun as good enough to overtake Werner or Davis. He saw Werner as valuable enough to warrant a contract extension, which was at least partially a reaction to losing two LB's to FA in the past two offseasons. Of course, I think anyone here would have preferred to give that money to Baun in hindsight. I can't imagine Werner ever turning in a season like Baun did in his first full-time starting year.
Loomis had us somewhat stuck with Davis due to excessive dead money on a 35 year old LB, which led to a contract extension last offseason to keep our cap in order. That's also money that could have been given to Baun, but it doesn't matter much since Allen didn't see Baun as worthy of starting snaps.