There is definitely a lot of middle infield bodies vying for A-ball playing time. A lot of names have been referenced above, but that's not including other guys like Nick Lockwood and J.D. Williams. Daniel Santana played a lot in CF after Grimes and Bryant showed up in June. When I saw him play, he look (understandably) uncomfortable out there.
My best guess (from last fall anyway):
Fort Myers: Tyler Grimes (SS), Daniel Santana (MINF/CF), Anderson Hidalgo (3B), Jairo Perez (3B/2B/OF), Reggie Williams (UTIL)
Beloit: Miguel Sano (3B), Eddie Rosario (2B), Tyler Grimes (SS), Adam Bryant (SS), Nick Lockwood (SS/2B), J.D. Williams (SS/OF), AJ Pettersen (SS)
EST: Niko Goodrum (INF/OF), Javier Pimentel (SS), Jorge Polanco (SS)
I also wonder if there is a chance that Rosario stays around in Fort Myers in April to continue how to learn the second base fundamentals and keep him out of the cold. I wondered the same about Sano, but he just seems too good. I know Revere and Hicks both started years in EST before coming to Beloit.