49ers cut ties with center Marcus Martin

The 49ers continue to make subtractions one day before the start of free agency, this time waiving former third-round draft pick Marcus Martin, a center who never played to his draft status.

Martin, 23, was the team's third pick in the 2014 draft. He started 24 games over the past three years, most of them at center, and struggled to hold his ground at the position.

The 49ers' starter at center has been Daniel Kilgore. When both Kilgore and Martin were injured in a game in Atlanta last year, Zane Beadles was forced to take over at the position.

Kilgore and Alex Balducci, who spent his rookie season last year converting from defensive tackle to center, are the only other players on the 49ers…