INDIANAPOLIS – The annual NFL Combine has been called "The Underwear Olympics" for the way players compete in a variety of physical tests in shorts and T-shirts, but it's more than that.

The weeklong gathering of media, coaches, scouts, front-office executives and player agents also makes it fertile ground for rumors, reports and speculation.

But the primary focus is on the 330 prospects who have been invited to be tested as part of the evaluation process for where they line up in the draft April 28-30. What should we look at?

Mike: In terms of position groups, the early indications are that the draft is deep in pass rushers and defensive backs. Those are two of the areas where the Lions could be looking for help.

With the 21st pick in the first round, there's bound to be a quality player available to the Lions at both positions.

The question will be what they value more highly – a pass rusher to upgrade an area that produced only 26 sacks in 2016, second fewest in the league, adding a playmaker to the secondary, or taking a player at another position.

And there are other positions of need, right?

Tim: There certainly are.

I would extend the need on defense not just to a pass rusher, but to upgrading the entire front seven. Defensive tackle is a position of need. Haloti Ngata, 33, isn't getting any younger, and three rotational tackles from last year – Tyrunn Walker, Stefan Charles and Khyri Thornton – are free agents.

The Lions certainly could use more impact from the linebacker position too. Lions GM Bob Quinn said after the season he believes DeAndre Levy can return to form after two injury-plagued seasons in 2015 and 2016. That would certainly help a position group that failed to record a single sack, interception or forced fumble last season. But even if Levy gets back to the player he was in 2014, Detroit could use always another impact linebacker.

Then there's the obvious need of improving the run game. It's going on 20 years now since the Lions were a consistent threat on the ground. Quinn has to decide whether that means adding a running back, improving the offensive line, or doing both.

Is there a player in particular you'll have an eye on during the testing?

Mike: Not to change the subject, or position – but I'm doing both.

The one player I'm most interested in is Jabrill Peppers of Michigan. I want to see how fast he runs the 40, and hear what the scouts and general managers say about where he fits best in the NFL.

Is it cornerback? Safety? Linebacker? Or is he an overall good football player that a team will find a place for him to play?

Peppers' time in the 40 won't provide the answer to his draft status, but it will be part of the equation.

Tim: It will be an interesting week for Florida State running back Dalvin Cook, and I'm not just talking about his on-the-field workout.

There's no denying his immense production and talent, but the medicals and interview process will be very important for him this week.

Cook's had several run-ins with law enforcement dating back to 2009, most recently in 2015. He's also had three shoulder surgeries. Will he get a clean bill of health from team doctors and then ace his interviews? Those two elements of the week might be just as important for Cook as running the 40-yard dash in 4.4 or 4.3 seconds.

Mike: You have raised the issue of character, and without pointing specifically at any player, it is something that has become increasingly important in how team's rate players. Health and injury history also are major considerations.

I had the Lions taking Dalvin Cook in my first mock draft, as the dream pick for teams from picks 1-21. The closer we get to the draft, dream picks are just that – dreams – and reality takes over.

At this stage – with a little more than eight weeks before the Lions turn in their card for who they pick in the first round -- reality points more to defense for the Lions by the day.

Tim: The good thing for Bob Quinn and Co. is that this draft is very deep at a number of positions of need, like pass rusher, linebacker, cornerback and running back.

Last year, in Quinn's first season running Detroit's draft, the offensive and defensive tackle positions were the deepest and most talented in the draft, and they also were positions of need for the Lions. Quinn was able to snag left tackle Taylor Decker and defensive tackle A'Shawn Robinson in the first two rounds.

I'm with you, Mike, when it comes to retooling the defense as a big priority. Detroit needs to find more impact players among their front seven. They need more guys who can get to the quarterback, get their hands on footballs and make more of an overall impact on that side of the ball.