What It Scores
BA is a valid word in the tournament list this site uses. Tile values only, before any premium square: 4 in Scrabble, 5 in Words With Friends, 5 in Wordfeud. The letters break down as B3 A1.
Anagrams of BA (1)
Same letters, different order. Any of these plays the same tiles for the same score.
Longer Words Containing BA
BA appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all, and the two and three letter lists. Full entry and definition at Merriam-Webster.