LineStar's sports betting analysts Shannon Sommerville and Tyler Wiemann break down today's top player prop bets and Home Run Calls for MLB action on 7/21/25. The best MLB Prop bets on both Underdog App and the PrizePicks App. AND our daily Home Run Calls- who we think will hit a bomb! Using LineStar's Props AI tool, we find the best value plays and MLB Player Prop Bets on PrizePicks & Underdog.