"I'm finally getting into the swing of running routes," Marshall told the Charleston (W.Va.) Daily Mail. "Running routes is the most difficult thing in the transition from quarterback. On this level, it's so hard not to tip off a (cornerback) and let him know what you're going to do.
"There are so many ins and outs to it. You can't really give away too much because the cornerback would be all over you. So, the more I work on that, the better I'll be at it."
Marshall should make the club and has a chance to suit up on game days. The 49ers would like to integrate his unique skills into the offense for some gimmick plays.
"I know I will be a punt returner," he said, "but I'm not sure whether it's first or second. That's up to me, I guess."
The 49ers believe they acquired a veteran cornerback who has a chance to earn a starting job. The team received Willie Middlebrooks in a trade with the Broncos. The 49ers sent defensive end John Engelberger to Denver to complete the deal.
Middlebrooks will compete with Ahmed Plummer and Shawntae Spencer for a starting job, coach Mike Nolan said. If he does not earn one of the top two spots, he should be able to fill the all-important role of the No. 3 cornerback. Second-year player Rayshun Reed and rookies Derrick Johnson and Daven Holly were the leading candidates for the No. 3 job prior to Middlebrooks' arrival.
Holly became the team's fourth draft pick to sign a contract. Receiver Rasheed Marshall, tight end Billy Bajema and tackle Patrick Estes are also under contract.
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