Based on the performance of their offensive line last season, along with the uncertain status of several free-agent defensive tackles, those appear to be the most logical positions for the Detroit Lions to target early in the NFL Draft.
With the Lions, however, you can never rule out trying to add another weapon offensively, especially with how that unit underachieved in 2014.
Lions general manager Martin Mayhew, like many NFL talent evaluators, is a big believer in taking the best player available as opposed to locking in an area of need, which keeps almost anything in play with the 23rd pick overall.
That includes receiver and running back, which was the focus Saturday, along with quarterback, on the second day of on-field workouts at the NFL Scouting Combine in Indianapolis.
Don't rule out the Lions seriously considering a running back like Georgia's Todd Gurley in the first round, according to NFL Network analyst Daniel Jeremiah, a former NFL scout.
The Lions haven't confirmed whether they plan to bring back Reggie Bush, who has two years remaining on his contract but could be a salary-cap casualty.
Mayhew has said that Bush's status is currently "up in the air."
"It's really about the value you bring to the organization," Mayhew said. "That's constantly re-evaluated every offseason."
Bush, who was hampered by an ankle injury much of last season and soon turns 30, would be worth about $1.7 million in cap savings if the Lions released him.
Knowing that, Jeremiah's pre-Combine mock draft projected Gurley to the Lions.
"The Lions have other needs, but Gurley might be too intriguing to pass up," Jeremiah said.
Gurley, who is coming off a torn anterior cruciate ligament in his left knee, chose not to run at the Combine. He still could do that at Georgia's pro day.
The Lions, it should be pointed out, haven't had much success recently in taking a chance on prospects with health concerns, specifically Jahvid Best (concussion) and Ryan Broyles (knee).
Asked what he looks for in a running back, Mayhew said, "I like guys with different traits. I want to build our roster with guys that can do different things. An all-around back is good.
"I like guys that are versatile. You've got to have a guy that can run between the tackles and you've got to have a playmaker who can do something in space."
Bush was signed as an unrestricted free agent before the 2013 season to provide the big-play threat in the backfield that had been missing after Best gave up football because of concussion issues.
But Bush rushed for only 297 yards on 76 carries, and caught 40 passes for 253 yards, in 11 games last season. He also scored just two touchdowns.
Theo Riddick, a 5-foot-9, 200-pound sixth-round pick in 2013, can do some of the things the Lions wanted from Bush, primarily as a receiving threat, while Joique Bell (5-11, 229) gives the team more of a physical element.
"When you have a guy like Theo Riddick who can make a difference in the passing game, that brings value to your team," Mayhew said. "Joique Bell, cleaning up between the tackles, running for us is big. He does a good job catching balls out of the backfield as well."
The value of running backs has diminished in recent seasons. None was taken in the first round in either of the last two NFL Drafts.
Some of the top running backs in the league have come from the second and third rounds, and even later.
Cincinnati's Jeremy Hill, a second-round pick last year, finished eighth in rushing as a rookie with 1,124 yards.
Pittsburgh's Le'Veon Bell (second with 1,361 yards) and Green Bay's Eddie Lacy (seventh with 1,139) were both second-round picks in 2013.
"The old first round for running backs is now the second round," NFL Network analyst Mike Mayock said. "They've been producing at a high level.
"This year is a little different with Gurley and (Melvin) Gordon at the top end."
Gordon rushed for 2,587 yards, the second-most in a season in NCAA history behind only Barry Sanders, and scored 29 touchdowns last season for Wisconsin.
Gordon has an "uncanny ability to make you miss," according to Mayock.
"If (Gurley) passes all that medical stuff, you can forget about the question whether we're going to have a first-round back," Jeremiah said. "We're going to have two of them."
Mayock, who has Gordon and Gurley 1-2 in his running-back rankings, described this as a "special draft class for running backs."
Therefore, with the depth that exists, the Lions could go find a replacement for Bush after the first round, if necessary.
"I think there are two that make a ton of sense," Mayock said.
One is Nebraska's Ameer Abdullah, according to Mayock, and the other Miami's Duke Johnson.
"You can get them in the second round," Mayock said. "That can replace a Reggie Bush."
Abdullah is a talented runner but he fumbles way too much, presumably because he has such small hands. Johnson might be the wiser choice of the two for that reason.
EXTRA POINTS
--- Michigan's Devin Funchess participated with the receivers and ran the 40-yard dash in a disappointing 4.7 seconds, leading Mayock to say it would likely "typecast him more as a tight end."
Neverthless, Mayock considers Funchess, at 6-4, 232 pounds, a "matchup nightmare."
"That's a big, long dude," Mayock said.
Funchess, who also dropped a couple passes in the drills, was projected as a possible top-20 pick entering the Combine.
His vertical jump of 38.5 inches was seventh-best among receivers, but would have been No. 1 for tight ends.
--- Michigan State's Jeremy Langford ran the 40 in 4.43, the fastest time unofficially of any running back at the Combine.
Mayock called him "sneaky fast."
--- Tony Lippett, another Spartan, was clocked in 4.61, "not a good number for a wideout," Mayock said.
Once he finished up the receivers' workout, Lippett was put through some additional defensive-back drills rather than having to wait around until Monday for the rest of the DBs to workout. He played both receiver and cornerback at MSU.
