Workouts for the league's pre-draft event begin Saturday.
Here are five things to watch this week in Indianapolis.
JOHNNY BE GOOD: Manziel is a dynamic player who may have more on the line this week than anybody else in town. After two sensational years at Texas A&M, he's trying to position himself to be considered the first overall pick by the Houston Texans. While the 2012 Heisman Trophy winner has said he will not work out next weekend, scouts will be looking at Manziel's height and weight to determine if he can hold up against the NFL's bigger, faster, stronger defenders. Coaches and team executives also will be eager to see how he handles the private interviews — the one part of the combine outsiders never see — to determine whether he's the guy they want as the face of their franchise for the next decade.
MICHAEL SAM: Last week, Sam became the first NFL draft prospect to acknowledge he is gay. This week, he'll face a media circus in Indy. He also has some questions about his physical ability to answer. The SEC's defensive player of the year was listed last season at 6-foot-2, 255 pounds, meaning Sam must demonstrate he has the speed and the agility to change directions to make it in the NFL. The heavy shift to 3-4 defenses has put a premium on heavier defensive ends, forcing lighter players to make the move to linebacker. If Sam demonstrates he's quick enough to be a pass-rushing end in a 4-3 front or athletic enough to move to rush linebacker in a 3-4 front, his draft stock should improve.
THE NO. 1 QUESTION: Manziel is only one part of the equation at the top of the draft. And if Manziel doesn't go No. 1, who will? That answer probably won't be settled after this weekend, though most analysts believe a quarterback will once again be taken with the first pick. If the choice is not Manziel, it could be Blake Bortles or Teddy Bridgewater. The Texans recently hired Central Florida's former college quarterback coach, and Bridgewater was considered the front-runner to be No. 1 throughout most of the college season. A year ago, at this point the odds-on favorite to go No. 1 was Utah defensive tackle Star Lotulelei. So a lot can change between now and May's draft, and don't rule out a possible resurgence by South Carolina defensive end Jadeveon Clowney.
JUNIOR JAM: A record number of college players (102) have given up their remaining college eligibility to jump into this year's NFL draft. While the first-round is sure to include plenty of underclassmen draftees, led by the likes of Manziel and Clowney, dozens of other early-entry draft hopefuls must show they're worthy of being drafted. If the underclassmen do well and go high, the trend of seeing more and more underclassmen enter the draft could continue in future years.
CHARACTER COUNTS: The toughest job this week goes to any of the players having to answer questions about their character. The list of indiscretions includes everything from arrests to drug-related suspensions to the use, or misuse, of Twitter. What scouts and team execs will try to do is sort fact from fiction as they attempt to figure out whether these were simple youthful missteps or a pattern of behavior that could continue to cause problems in the future.