Stanford offensive tackle Cameron Fleming will graduate early and pass up his senior season. (TONY AVELAR/Associated Press)

Ask any NFL talent evaluator about the quality of this year’s draft class, and there will be a familiar refrain. They’ll tell you they’ve never seen a crop of talent this rich from top to bottom.

Officials and scouts began anticipating a promising class back in the fall based on the play of the nation’s top seniors. And then a record 98 players opted for early entry, adding to the talent bounty.

“This is the best draft,” Pittsburgh Steelers General Manager Kevin Colbert said Thursday as the NFL Scouting Combine got underway at Lucas Oil Stadium. “I’ve been doing this for 30 years, and this is the deepest draft that I’ve ever seen.”

At first blush, the bumper crop sets up NFL teams with a positive situation. Not only will they find talent in the first couple of rounds of the draft, but they also expect to have no problem finding skilled, promising prospects in the middle to late rounds.

But the depth also presents challenges.

The bulk of the research conducted by scouts during the college football season involves evaluating seniors — the only sure things when it came to incoming talent. Other eligible players had until Jan. 15 to declare for the draft. Those decisions sent teams scrambling.

“When you go into a school and you’re scouting in the fall, you’re focused on the seniors,” Tennessee Titans GM Ruston Webster said. “You don’t get quite the same look. You’re [now] playing catch-up the best you can.”

Said Patriots Coach Bill Belichick, “This is the heaviest underclass group that’s come out. So a lot of those players weren’t surprises, obviously. But because of the large numbers of them, plenty of them were.”

The early-entry total spiked significantly this year. Last season 73 players declared early for the draft. Of the 98 featured in the 2014 draft class, 85 received invitations to the combine, where they joined 240 seniors as they go through physical and psychological evaluations and interviews with teams.

Interviews and evaluations will prove crucial for all of the players but especially for the early entrants.

“The juniors added into it make it a very talented group,” Colbert said. “But the one thing that we talk about with these juniors — or any of the underclassmen, the redshirt sophomores — we are very cautiously optimistic about their emotional and physical readiness for this. This is a huge jump.”

Early-entry players will insist to talent evaluators that they have the mental fortitude to handle the leap. But teams can’t just take them at their words. They will interview college coaches, teammates, friends, teachers, family members — anyone they can to get a better idea of a player’s mental makeup.

“It’s an educated guess. We just keep our fingers crossed,” Colbert added. “Experience has told us that a lot of these younger players aren’t ready for this. It’s a huge leap. I don’t think a lot of them understand that until they are actually on a playing field and see the increase in the quality of play. That’s the physical part. But the emotional part of being a college kid and all of a sudden the next day being a professional, I think it’s a little easier to transition from your senior year to the pros than it would be from a junior or sophomore year.”

Some are more mentally mature than others.

UCLA guard Xavier Su’a-Filo, for instance, is a junior. But at 23, he also has a two-year Mormon mission under his belt that delayed his college career.

Then you have players such as Stanford offensive tackle Cameron Fleming, a redshirt junior, who will graduate with his degree in aeronautics and astronautics and forgo his final year of eligibility. Some scouting reports suggest Fleming — a projected late-round pick — could benefit from another year of playing college football.

Fleming disagrees.

“My parents kind of gave me permission after I told them I’d graduate this year, and I decided to come out this year because I played three years at Stanford, started and figured that this was the time to take the next step,” he said.

Some players have elected to leave school early for academic reasons or because of unfavorable situations on their college teams — or just because they believe the move to declare for the draft will better benefit their families rather than waiting another year.

Tennessee State tight end A.C. Leonard recorded 51 catches for 733 yards and six touchdowns as a sophomore but had just 34 receptions for 441 yards and five touchdowns as a junior. Although he’s projected to go late in the draft, he said he talked to his grandparents and decided that leaving school was the best move.

California redshirt sophomore tight end Richard Rodgers also ranks among the late-round projections. But Cal’s offense doesn’t use the tight end much, so Rodgers decided to leave.

“That’s a big thing. If you don’t have tight ends in your offense, then you can’t be utilized,” said Rodgers, who tallied 39 catches for 608 yards and a touchdown last season. “I just felt like it was just my time to go because I can reach my full potential by going to the next level to play tight end. It’s always a risk when you take a step to the next level, and you can’t control that. But that’s the risk I’m willing to take.”