It's definitely not any Hot Springs baseball field I'm aware of. The Red Sox were at Majestic Park in the spring of 1915, and this isn't definitely isn't Majestic Park. The other image Scott posted in #4 does in fact look like Majestic Park though. Here's some other Majestic Park photos from that era for comparison:
https://www.flickr.com/search/?w=914...N07&q=majestic