The biggest question on defense this spring for Georgia Tech coach Paul Johnson is not having a new coordinator on the field.

It is having some of his best players on the sideline.

Johnson said Tuesday that three starters will be out when spring practice opens next Monday -- linebackers Jabari Hunt-Days and Brandon Watts and safety Isaiah Johnson. Safety Fred Holton, who missed all of last season with a foot injury, won't be full-go for spring, either.

"We have a couple linebackers out and couple guys in the secondary but what it’s going to do is give the young guys a chance and hopefully we’ll be able to develop some depth that way," Johnson said.

Starting center Jay Finch also will miss spring practice, along with A-back Tony Zenon and freshmen receivers Anthony Autry and Travin Henry. B-back Charles Perkins, who opened 2012 as a starter but sustained a season-ending injury in early September, should be back. Johnson said, "We’re counting on him, but we really won’t know for sure until we get out there and start banging a little bit."

There also are a few position changes to note on defense. Jeremiah Attaochu will become a full-time defensive end, after he thrived in that role in the second half of last season.

And Jemea Thomas is moving back to cornerback after switching to safety in 2012. He will be leading the competition to take Rod Sweeting's starting spot. Johnson said of Thomas, "He may have been our best defensive back a year ago."