After thinking about this, I think it makes sense to a degree. Having the 38th, 39th, and 40th slots "flexible" (i.e., players you can cycle through) has two benefits. 1. There is always a chance that you can pick someone up on waivers who will really catch fire and have a huge hot streak. See Perez in 2015-2017 and Sogard in 2017 for a examples of this, as well as Saladino and Choi this year. On the pitching side, see Dan Jennings. That may make a win or two of difference over a season. The Crew was within one game of the playoffs last year. Perez has gone, IMO, from one-year wonder to a crucial piece on the bench. 2. When you have a very hot prospect you need to bring up, like Josh Hader, Freddy Peralta, etc., it may not be a bad idea to have someone you don't mind jettisoning.