INDIANAPOLIS — The Indianapolis Colts today started their first of 10 OTA workouts at the Indiana Farm Bureau Football Center. What are some key storylines to keep an eye on over the next three weeks?

» An expanded offense?: Entering Year 2 under head coach Frank Reich, the Colts' offense could very well start to evolve in its complexity as the next few weeks move along. During OTAs, teams can begin conducting 7-on-7, 9-on-7 and 11-on-11 drills with helmets (though no live contact is allowed), so, for the first time this offseason, the Colts will get a chance to simulate more traditional practice-like settings. The fact that so many of Indy's key pieces on the offensive side of the ball return this season means that the majority of those on the field will be able to carry everything they learned about the system last year into 2019, and then all the playbook additions and adjustments made on top of that should be relatively simple to pick up. "Now there's other variations that we've talked about, and that we talked about last year, like, 'OK, hey, we're gonna start with this, and then here's going to be a complement to it,' and some things we got to, some things we didn't get to — because we didn't need to," Reich told reporters back in March at the NFL owner's meetings. "You know, don't outsmart yourself; if it's working, sometimes what happens is you do something that's working, you've got something to complement it, and all of a sudden you back off of it because you think they're gonna figure it out, but they never do. So that's the challenge — you know, figure out, 'Hey, let's not give them too much credit, but let's keep being creative.'"

» New pieces on defense: Matt Eberflus has a few new toys to play with on the defensive side of the football for the Colts. It started back in March when the team signed free agent pass rusher Justin Houston, who adds his double-digit sack potential to an already-talented defensive front. Then, last month, the team added seven new defensive players via the NFL Draft — three at linebacker, two at cornerback and one each at safety and defensive end. The added speed and athleticism all around could very well make Indianapolis' defense one of the quickest in the entire league. This should be most apparent at linebacker, where the team added Ben Banogu, Bobby Okereke and E.J. Speed, all of whom will be expected to play all three spots (WILL, MIKE and SAM), but, in Banogu's case, especially, he can also slide inside and get after the quarterback on passing downs. The Colts in 2019 seem to be facing an elite offense and/or quarterback week after week — especially on the road — so general manager Chris Ballard wanted to make sure his roster was full of guys who can "hawk the quarterback;" we'll see how those position groups begin that process over the next few weeks.

» Roster battles: The OTA sessions are really the first opportunity to conduct practice-like settings, so these next three weeks will be the first opportunity to actually see where certain players are beginning to line up, and how reps are distributed at various positions. One thing's for certain: you'd be hard-pressed to find anybody who'd be willing to list with any degree of certainty what they feel the Colts' current depth chart would be at wide receiver, linebacker or cornerback, specifically, past the first one or two spots. It will assuredly make for some intriguing battles during OTAs, minicamp, training camp and the preseason, and, if it's done right, Reich and his staff will be left with some extremely difficult decisions when they cut down to the 53-man regular season roster in late-August/early-September. "I am looking at the board in there right now as the names are being put on there. I am saying, 'This is going to be tough,'" Reich said after the draft. "And it's hard because you really develop a closeness and bond to every one of these players. You just know that's the nature of the business and the good thing is guys are pros. They know this is the cream of the crop, this is the best of the best, this is the NFL and every year it's going to happen. As a player, you welcome it because you know it brings out the best in you. It will be tough decisions."

» Welcome to the NFL: The Colts will enter OTAs with 16 rookies on their 90-man offseason roster, and they all will pick things up at their own pace. Those who can learn on the fly the quickest, of course, will start to get a leg up over the course of the next few weeks. Also, remember these names: Ashton Dulin, Penny Hart, Cole Hedlund, Hale Hentges, Jegs Jegede, Johnny Robinson, Shakial Taylor and Tre Thomas. Chances are at least one of these guys will make the Colts' Week 1 roster, as the team has had an undrafted rookie make its initial 53-man roster 20 years in a row (2019 would be the 21st straight year). In 2018, it was linebacker Skai Moore and safety George Odum who were able to overcome the odds and make it to the Week 1 roster as undrafted rookies; who will start to pave their own similar path starting today?

» Injury watch: We already know a few key Colts players will either be brought along slowly the next few weeks, or miss the OTAs and minicamp entirely, as they continue to work their way back from various injuries. Those who are expected to miss the rest of the offseason workout program and return for training camp are linebacker Darius Leonard, wide receiver Deon Cain and tight ends Jack Doyle and Ross Travis. Those who could be on and off the field throughout OTAs and minicamp are tight end Eric Ebron, safety Clayton Geathers, wide receiver T.Y. Hilton and linebacker Anthony Walker.

» No. 12: Last year at this time, Andrew Luck was just about ready to start implementing a regulation-sized NFL football into his throwing regimen after his shoulder surgery caused him to miss the entire 2017 season. By the time training camp rolled around, Luck was full-go at practice, and he would end up putting together perhaps his best-overall season in the NFL, earning league Comeback Player of the Year honors. Luck in 2019 is fully healthy during the offseason for the first time in years, and he'll be able to pick up where he left off and take all the reps needed with the No. 1 offense from Day 1 of OTAs. Whether or not Luck ends up taking 100 percent of the first-team reps, the fact that he'll be able to actually work on the field with his teammates — and continue to build a rapport with new targets like Devin Funchess and Parris Campbell — is already an improvement over last offseason.