Hotel-wise, Holiday Inn Sunspree is probably your closest beachfront location and it is nice. It is on Front Beach Road (roughly middle of the beach).
If you decide to go the condo route, you can get closer to your baseball destination by staying on Thomas Drive. I would check VRBO.com. There are many properties, but you might consider Seychelles (has the type unit you are searching for and is convenient). Also, we like Pelican Walk (an older place, but quiet and well maintained).
If you aren't comfortable with the VRBO thing, you might try Joni's Beach Rentals...we have rented through them several times and they are good to work with.
3 nights is probably doable for a condo, although you'll need to seek out the good nightly rates to balance the cleaning fee they all charge regardless of the length of stay.
Have a good trip!