Just got back from Tucson and if you are going for games at the University of Arizona, I highly recommend the University Park Marriott that is "practically on campus" and...right next to Starbucks, a big plus for me....http://marriott.com/property/propertypage/TUSUP. Really, really nice hotel with a great area of shops and restaurants surrounding it.
If you are going for a tournament at some of the minor league ballparks, a different location would be closer to those.
If you want something also close to the University and very upscale, the Arizona Inn would be a good choice.
http://www.arizonainn.com/But with baseball players, you usually don't want/need upscale
.