Boyko was a four-year starter at left tackle in college, but the NFL is not the Mountain West, and he lacks the athleticism you typically want from a tackle at the professional level. He played both tackle and guard for the Philadelphia Eagles during the preseason/training camp. Once upon a time, people thought his best position might eventually become center, but that is probably not something he will be asked to do in San Diego thanks to the number of guys already lined up at the position.
An undrafted free agent last year, Boyko initially made the Eagles roster but spent the regular season on the practice squad. He is probably more of a camp body than actual competition to make the roster, but players can surprise you and the Chargers are looking to solidify their offensive line depth after the last two seasons.
UPDATE: It's now official. Zeth Ramsay has been waived to make room.