"If I were to create a website for every baseball team, would it be best to create each site individually and link them together?"
Before Panda.... one website for one team was something that can be considered.
After Panda.... only one website should be better, and teams can be arranged in sub-folders. I don't see any use of keeping several sub-domains. Sub-domains makes sense when it comes to functionality of website. Can keep customer support, forums or blog in sub-domains. But sections of website's one topic looks good with folder.
There are around 30 different teams which you'll need to consider. So sub-domain for each team is definitely, a NO-No.
Hope this helps!