EARTH CITY, Mo. -- The St. Louis Rams officially began organized team activities on Tuesday but Thursday brings with it the first session open to the media. That includes yours truly, and I'll be back later with thoughts and observations from the day's work.

Earlier this week, I looked at three main storylines to monitor as OTAs roll on: the defense's ability to take the next step to a top-10 or top-5 unit, quarterback Nick Foles' adjustment to an offense far different from the one he left in Philadelphia, and the ability of what projects to be the league's youngest offensive line to mesh before the season.

Greg Robinson, who is coming off a foot injury, is expected to continue to work during OTAs. Jeff Curry/USA TODAY Sports

Here's a few leftover things on a more micro level that I'll be watching as we get a closer look at this year's edition of the team:

In the zone -- Since hiring Frank Cignetti Jr. as offensive coordinator earlier this offseason, the Rams have dropped some hints at some tweaks to the offense. One such tweak that's expected is that they'll add more zone-blocking schemes to the mix than they've done in recent years. That doesn't necessarily mean they'll scrap some of the power schemes they've used in the past but that the Rams are looking for ways to be more versatile offensively. Namely, adding more zone offers some new ways to rev up the run game the Rams hope to have. We won't know until games start how the Rams plan to mix it up, but it's a new wrinkle for an offense that could use some.

The man in the middle -- There will be plenty of attention paid to the offensive line in the next few weeks and into training camp, but the biggest position battle on the roster comes at center. The Rams have three primary contenders to be the new starter in the middle in Tim Barnes, Barrett Jones and Demetrius Rhaney. Barnes figures to get first crack if only because of his experience (he's started four games to the others' zero), but the Rams seem to hope that Jones can finally emerge in his third season. Rhaney is more of a sleeper but don't underestimate his toughness, a quality line coach Paul Boudreau likes in a pivot.

Todd Gurley's status -- Rookie running back Todd Gurley won't be fully participating in these OTAs, but we should get a glimpse of how far along he is in his rehabilitation from a torn left ACL. At last check, Gurley was able to run but hasn't been cleared and doesn't yet have the ability to move laterally like he will need to when he's on the field. Even after OTAs, it's unlikely we'll know when Gurley will be able to play again, but we should at least have a better idea of how close he is to that end.

On the mend -- Gurley isn't the only Ram coming off injury that bears watching. Receiver Brian Quick (shoulder), guard Rodger Saffold (shoulder), tackle Greg Robinson (foot/toe) and end Chris Long (foot/ankle) are either coming off an injury that slowed them in 2014, ended their season, had offseason surgery or some combination of the three. Quick isn't likely to participate but should be far enough along to get an idea of where he is in his rehab process. Robinson, Saffold and Long are expected to be ready to go. Rookie receiver Bud Sasser still has not been cleared to practice after a medical condition kept him from passing his physical upon arrival. His status should get clarity as soon as today.

Linebacker limbo -- With all 11 starters returning on defense, the Rams don't have much in the way of questions about what they have on that side of the ball. But there is one competition that will be worth watching over the next few months: strongside linebacker. Coach Jeff Fisher has said incumbent Jo-Lonn Dunbar and newly-signed Akeem Ayers will battle for that job. Ayers offers more pass-rush production but Dunbar is considered the better run defender. The Rams also have safety Mark Barron, who worked as a de facto third linebacker toward the end of last season. As it stands, Ayers looks like the favorite but time will determine a winner.