I highly doubt that it would be treated like a shot clock or play clock. It has no effect on the viewer, it is just an impartial reminder to the players about following the rulebook-defined pace. I'd wager that within a month or two, it wouldn't even have any effect on the players, they would already be trained to follow that pace again, just as they have done for the rest of their baseball careers (high school, college, minors). There is no purely "natural" solution to this problem. You can't do any umpire-based solutions -- umpires will fail to enforce them effectively, just like the pace-of-game initiatives from a couple years ago, and just like umpires already liberally allow time to be called, just because they want to avoid conflict. And I don't necessarily blame them. But that means you need something external and objective that they will follow just like the players, hence the clock. Just installing an external, objective clock to remind players of the already defined rulebook pace is the most "natural", effective solution you will find. It doesn't really add or change any rules. Do you know there's already a between-innings clock in MLB? At least, I have seen it at Target Field. Doesn't really have much effect, because between innings time isn't the root problem, but it just exists in the ballpark, the umpires and players follow it, and the fans ignore it. There's also a pitch clock in the minors that is treated similarly.