Bobby Williams was asked how many players he will need to replace Brenden Schooler on special teams.

“I can’t answer that question,” Oregon's second-year special teams coach said following Friday's practice.

Schooler has been a contributor to multiple coverage and return units for the Ducks while earning first-team all-Pac-12 honors during each of the past two seasons. He was credited with seven tackles in each of those years.

Oregon expects to be without Schooler for the first four or five games of the season after he suffered a foot injury in practice last week and underwent surgery Monday.

“We are trying to look at a lot of guys, a lot of freshmen,” Williams said. “Teach them the whats and the hows and those types of things because those things are important.”

Williams has a few position battles to monitor, including kicker and punter.

Junior Adam Stack was Oregon’s primary punter as a freshman and kicker as a sophomore and remains in contention for each of those spots after batting a nagging injury for much of last season when Williams noted he had to “manage his workload throughout the week to get him to the game.” Stack was 6-for-10 on field goals with a long of 39 yards.

“Now we are in position where we can take him through a normal week and he’s able to perform when needed to,” Williams said. “The first week, we’ve done quite a bit of field-goal work and we try to manage our distances as we go throughout camp and put them in situations where we call for a field goal in the middle of practice, like a game, and the distances can vary. He’’s done a great job so far.”

Freshman Camden Lewis is in the kicking competition along with junior Zach Emerson, who handled kickoffs last year.

Oregon split punting duties between Blake Maimone and Tom Snee last year as both return.

“You always want one guy to be the guy, but if one guys does something better in one area and the other in another area, you have to utilize two guys,” Williams said. “They both have different features and have done a great job.”

Seeking third running back

If CJ Verdell and Travis Dye lead Oregon in rushing again this season as expected, Jim Mastro will be looking for one more running back to fill out a rotation in games.

“You want to get about 2½ guys ready for every game,” Oregon’s second-year running backs coach said. “The best 2½ in practice that week will play.”

Mastro has a couple of seldom-used sophomores along with two freshmen vying to get the work behind Verdell and Dye, who combined for 342 of Oregon’s 529 carries last season.

Darrian Felix ran for 182 yards and a touchdown on 30 carries as a freshman before suffering a season-ending ankle injury against San Jose State last year that limited him to 14 carries for 47 yards in two games.

“Darrian, if he just stays healthy, is as talented as they come,” Mastro said. “We have to keep him fresh and healthy. He is behind the eight-ball a bit because he missed almost all of last year.”

Mastro said Felix is the fastest of the returning running backs.

“He’s got a little bit of (Dye and Verdell) put together, but he’s dynamic,” Mastro said.

Cyrus Habibi-Likio was primarily a short-yardage back last year when he had 18 carries for 36 yards and seven touchdowns.

Sean Dollars, a 5-foot-10, 204-pound back from Mater Dei High School in Santa Ana, Calif., is Oregon’s top recruit at running back. Jayvaun Wilson is the other new running back on the roster.

“Sean is going to be a real good player,” Mastro said. “Right now they are swimming because we are asking them to lean a lot. Sean can do it all. Our running backs here have got to know a lot and he is picking it up. He’s a smart kid so once he picks it up and knows it, there won’t be as much thinking going on. Right now the play is called and he thinks a lot. Once he gets that, he’s everything we thought he was.”