SANTA CLARA -- Demarcus Dobbs and Will Tukuafu are roommates who share a unique role among NFL players.Both players were converted to two-way performers in the offseason, and both served significant dual roles during the exhibition season.Dobbs and Tukuafu came to the 49ers as defensive linemen. Now Dobbs wears No. 83 (so he does not have to report before every offensive snap) and also plays tight end. Tukuafu doubles as an imposing 292-pound fullback.I asked Dobbs how he answers when people ask him what position he plays."I tell them I'm a mutt," Dobbs said. "I'm just a mutt. I do all types of different things -- all types of breeds. I just tell them I'm defensive lineman but I do pretty much everything."I do take pride in being a mutt. There aren't many mutts around this league. Mutts are always a better dog, anyway."Coach Jim Harbaugh has an affinity for two-way players. He made Owen Marecic major college football's only two-way player at Stanford. Last season, the 49ers used nose tackle Isaac Sopoaga for 42 snaps on offense at fullback. Harbaugh also employed Justin Smith during the playoffs as an extra blocker.Tukuafu and Dobbs were both converted into two-way players in the offseason. Dobbs played both ways in all three exhibition games in which he appeared. Tukuafu did not see two-way action in training camp until after the first three weeks of camp. He concluded the exhibition season in impressive fashion."He was crushing people," Justin Smith said. "You didn't even have to see it. You could hear it. I know I wouldn't want to take on a 290-pound fullback. I'm sure Green Bay's hoping he's just a gimmick and (we) won't use him that much. He put some pretty impressive stuff on tape."In the past two exhibition games, Tukuafu played 31 snaps on offense and 42 snaps on offense, respectively. He had two devastating blocks against the Chargers, including one that cleared the way for Anthony Dixon's touchdown run in the first quarter."He was a mutt before everybody else knew he was a mutt," Dobbs said of Tukuafu. "We went into the same thing at the same time. He went to fullback, and I went to tight end. I guess I got the bulk of the press before he did."He had an incredible game against San Diego. We're roommates when we go on the road. Will and I are close. To see him succeed and do what he did in the game made me happy. I got goosebumps watching him play the game."Harbaugh suggested Dobbs could be asked to expand his role even further. With Parys Haralson out for the year with a left arm injury, Harbaugh said it's a possibility Dobbs (6-foot-3, 285 pounds) could also see time at outside linebacker.That would not appear to be necessary in the 49ers' first two regular-season games, as the 49ers are likely to spend most of the time with extra defensive backs on the field to defend the high-powered passing attacks of Green Bay and Detroit.When the 49ers go with extra defensive backs, starting outside linebackers Aldon Smith and Ahmad Brooks shift to defensive linemen to rush the passer. Dobbs was used in exhibition games as a backup outside pass-rusher in nickel situations.