Vaughn is cheap at $9 million for a guy who would be a reasonable starter at 1B or DH.
It is important to note that Yelich's playoffs are overshadowing his bad year. In many ways, Vaughn as a full time DH with Yelich getting occasional playing time would be better. Yelich may also hit a cliff this upcoming season. He had a barely playable at DH wRC+ of 99 versus RH pitching. The risk of Yelich just not having it anymore plus his ongoing health concerns means you want depth here.
I'm as big a supporter of Adams as anyone and miffed he didn't get into the top 5 minor league hitters on this website. A wRC+ of 149 in AAA is very, very good. However, his inability to stay healthy is an issue. He has not had a full season of PAs in either 2025 or 2026. Hard to rely on him to be depth until he can show he is available.
Burke was lost in AAA and needs to prove himself there. Similarly Fisher is another high K guy who should at least show he can handle AAA pitching before being promoted. The Brewers track record with high K prospects is not great.
Would you move on from Vaughn if you were expecting to win 75 games giving minor league depth? Easily. But when you are going for 95+ wins, depth is important.