While the changes on defense this offseason have dominated a lot of the headlines, the offense, though returning coordinator Jim Bob Cooter and quarterback Matthew Stafford, has made some changes too. They've revamped the run game and tight end position, and have a new offensive line coach with new blocking schemes.

Detroit ranked seventh in scoring last season and sixth in passing, but there's still some question marks surrounding that side of the ball heading into training camp.

So with that, Tim Twentyman and Mike O'Hara continue to address some of the key training camp questions facing the club:

Monday: Best position battle heading into camp?

Tuesday: Which player could surprise Lions fans in training camp?

Next up is a closer look at the offensive side of the ball.

3. Which position has the most to prove on offense?

Mike O'Hara: Wide receiver

Wide receiver is a surprise choice, and it's not made because I don't think it's a good group.

It's just the opposite. The wide receivers made up the offense's best unit last year, and they have to back it up this year with some of the personnel changes on offense.

There's a lot to like about the Lions' receivers, both individually and as a unit.

Marvin Jones Jr. was a deep threat last year with 1,101 receiving yards, nine TD catches and a league-high 18.0 yards per catch.

Golden Tate had his fourth straight season with at least 90 catches (91 for 1,002 yards and five TDs.) He led all wide receivers with 639 yards after the catch, continuing his open-field wizardry with the ball in his hands.

Rookie Kenny Golladay had a promising beginning to his career with 28 catches, three TDs and 17 yards per catch in only 11 games.

It was a big year for the receivers, with solid depth behind the top three.

It remains to be seen how they're affected by offensive changes. Lack of an established receiving tight end could create a bigger burden, but an improved running game could create opportunities.

Either way, it should be an interesting season for a talented group.

Second choice: Tight ends. Stafford hasn't had a high-volume receiver at tight end since Brandon Pettigrew had receiving totals of 71, 83 and 59 catches and 12 TDs from 2010-12. Nobody in this season's group has shown that he will come close to that production. Whatever they accomplish is likely to be as a group effort, but there's an opportunity for someone to take a leap forward.

Tim Twentyman: Offensive line

Football games are won and lost in the trenches. The five players up front for the Lions have to prove they can stay healthy and play as well as they look to be on paper.

Detroit started 10 different offensive line combinations last season. It's hard to be consistently good on offense when that's the case. The best ability is availability.

The Lions have added power and explosiveness to their running back room with the additions of veteran LeGarrette Blount and rookie Kerryon Johnson, but there still has to be holes for them to run through. Last season, Lions running backs were stuffed behind the line of scrimmage on 27 percent of their runs, per Football Outsiders stats. Only Seattle had a worse percentage (30).

Stafford endured 47 sacks last season. While not all of those are the fault of the offensive line, that's where the protections and communication starts.

GM Bob Quinn has spent two first-round picks (Taylor Decker, Frank Ragnow), a third round pick (Graham Glasgow) and two priority free-agent signings (T.J. Lang, Rick Wagner) on putting together this offensive line in Detroit. It's time to make good on that resource allocation.

Second choice: Running backs. The Lions haven't had a 100-yard rusher since 2013, and Stafford has only had one for seven games in his nine-year career, which is still an amazing statistic to me. The Lions have ranked no higher than 23rd in the NFL in rushing in eight of Stafford's first nine seasons in the league. What could this offense be if they got more production from the running back position?

Looking ahead at Thursday's question: Position with the most to prove on defense?