Despite the departure of Joeckel, the Aggies still return six starters on offense.
The Aggies also took a big hit on defense with star defensive end Damontre Moore also leaving early for the draft.
"You've always got a new group of guys coming in," defensive coordinator Mark Snyder said. "Guy gets injured, another's got to step up. But it gives guys the chance over spring ball to show us they can contribute."
Sumlin isn't worried about his team handling increased expectations after its surprising success last year.
"That's OK. That's part of it," he said. "I would rather it be that way than nobody talk about us at all. That helps recruiting, that helps everything."
Sumlin hopes to have his two-deep roster set by the end of spring practices. If he doesn't, he at least wants to have a clearer idea of who is in the mix to start at each position.
"We've got a number of players on this list, this two-deep, that haven't played," Sumlin said. "I think we've got to get a number of these guys who have been role players ready to be serious contributors in this program. At the end of spring practice, that's going to be the big evaluation individually."
The Aggies will have to wait to see the progress of several injured players who won't be healthy enough to participate in spring drills. Linebacker Justin Bass (knee), defensive lineman Kirby Ennis (knee), linebacker Steven Jenkins (shoulder), running back Trey Williams (sports hernia) and defensive lineman Ivan Robinson (Achilles tendon) will all sit out this spring.