CINCINNATI -- In the 2013 offseason, the Cincinnati Bengals focused on the institution of the two-tight end set.

Much of the 2014 offseason thus far centered around the absence of two tight ends.

Both Jermaine Gresham and Tyler Eifert missed the second week of organized team activities that began Tuesday.

Eifert spent much of Tuesday working out on the side while battling a shoulder injury.

Gresham's injury is unknown and his presence unaccounted for. Gresham was around the facility throughout Phase 2 of the offseason program, and coach Marvin Lewis said the fifth-year tight end was rehabbing at the facilities, but Lewis wouldn't delve deeper into the situation.

"He's just not out here because he's not practicing," Lewis said. "He's doing what he has to do."

Bottom line: Lewis anticipates Eifert and Gresham will be ready for the beginning of camp. The team will need both. The duo combined for 85 receptions for 903 yards and three touchdowns last year. With new offensive coordinator Hue Jackson re-emphasizing the running game, the power and versatility of two-tight end sets will be a staple.

Eifert at one point wondered how much he would be a part of the scheme this year. At the end of last season, his rookie year, he sustained a neck stinger that limited him to three snaps in the playoff loss to the San Diego Chargers. His nerves also were rattled when assessing the big-picture ramifications of a neck injury.

"I trust the doctors," said Eifert, who caught 39 passes for 445 yards and two touchdowns during his rookie season. "I was a little nervous because if you play football, you are going to get stingers and things like that, but this was kind of unlike any one I've had. From that standpoint, it was a little worrisome, but I knew I was in good hands and they assured me that I'd end up being all right."

The first-round pick out of Notre Dame took on a variety of roles, including that of a moving tight end who flashed into the fullback position periodically. On a team with Gresham, wide receivers A.J. Green, Marvin Jones and Mohamed Sanu and running back Giovani Bernard, finding ways to produce numbers up to first-round expectations proved difficult. He didn't transform the offense as much as many predicted.

"Offense obviously has a lot of playmakers," Eifert said. "It's hard to get everybody the ball a lot. It's almost impossible to do. Last year I think I created headaches for the defense. Whether I was catching the ball or not it was something they had to game-plan for."

He believes as long as he arrives at the season healthy along with his running mate, Gresham, the possibilities exist for the combo to grow on their 2013 production.