THEME:   baseball diamond grid with circled letters as baselines spelling ways to advance runners   
GOOD ONES:     What the circled words (shown in the appropriate direction) are capable of doing   ADVANCING THE RUNNER   
Ones getting lots of Bronx cheers   YANKEES [does this mean cheers for the Bombers or boos?]      
BTW:   Baseball commissioner under whom interleague play became a reality    SELIG [only needed the first two words]      
Spanish pronoun   ESTA [rather than grammar, why not clue it the way it may be heard: "Como ESTA usted?"]         
This was a particularly creative way to recognize the opening week of Major League Baseball, so as a fan...   
RATING:    
 
 
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun