This whole argument is incredibly flawed.
1. Before their breakouts this season, Zach Cozart and Tim Beckham would have only been a mild upgrade (if any) from Barney (both are the type of guy I'm talking about that you'd take a shot at and hope he takes a step forward. You now have to find the "next" guy to do that).
2. Neil Walker is a starter in MLB. You're not trading for a guy making $17M to be a bench player (especially since he can't play SS).
3. Jed Lowrie might be your best example, but prior to this season you would have been trading for a guy who's set to make $6.5M, coming off a -0.8 WAR season when you already have Barney making $2.9M coming off a 1.5 WAR season. Oh and he can't really play SS either.
As I said, if you want to find a better utility IFer for the 2018 season, you're looking to find the next Tim Beckham or Zack Cozart. That player is probably coming off a failed season or two with a team giving up on him. You have to trade for that guy and then hope he makes significant improvement. Or you could be looking for someone coming off a bad season, who's still owed some dough. Again, a risky move. These guys are not easy to find. The sure things are either on WS contending teams, or they are starters on other teams (or looking to be if they are a FA).