The defining point of the Steelers' fourth-round draft pick in 2013, Shamarko Thomas, is likely the flailing effort he put out as Patriots tight end Rob Gronkowski plucked a perfect catch out of the air for a touchdown. Thomas was targeted frequently enough by Tom Brady and the Patriots in one of the most dismal Steelers' defensive performances ever - certainly of the Mike Tomlin Era.

At that point, the Shamarko Thomas Nickelback experiment was all but over.

The Steelers said this offseason Thomas would go back to playing safety, and just safety. No experimenting with him in man coverage in the slot. Some special teams, but primarily, he'd be a back-up safety, waiting on his chance to get in the game.

Logic might suggest to most wannabe cap analysts the Steelers extended the contract of veteran safety Troy Polamalu in an effort to get one more year out of him while spreading his cap charge over the next three seasons. The implication in that is Polamalu would be released post-June 1 in 2015, allowing the team to essentially account for $10 million over the three years of the deal he signed in 2014 - $6.3 million last year (down from $8.25 million from before his deal), $2.25 million in 2015 and 2016.

Many immediately gawked at the deal, viewing it as the Steelers paying older players too much money for too long a time. It would seem likely Polamalu, who may retire, will not be on the Steelers in 2015, and the team simply found a way to make good with him on the money they were scheduled to pay him, keep him for one more season while Thomas develops and be able to shed the remaining cap obligations into future years in which the cap was increasing.

That all seems to be in line right now, except for Thomas's development. He didn't get into the secondary in 2014, being passed over for veteran Will Allen (who remains unsigned for 2015). Some of that had to do with injuries, as Mark Kaboly of the Tribune Review points out. Perhaps it also was done out of the feeling the secondary needed experience within the defense, and with 2014 signee Mike Mitchell already in the deep secondary, the Steelers wanted a veteran who'd played in the defense before.

While Mitchell will have a level of experience in 2015, Thomas, assuming he's the guy to replace Polamalu in the event the veteran is cut loose, will not. If it was an issue in 2014, the team did little in terms of snaps to prepare him for 2015, either.

Thomas has trained with Polamalu, and won't talk about replacing his mentor. It's hard to gauge Thomas's development due to injuries and a lack of playing time, but the things fans don't know are what drive decisions regarding the roster and salary cap.

Thomas, as unknown a commodity as he is (keep in mind, too, the Steelers dealt a 2014 draft pick back in 2013 to move up and get him), his availability for 2015 could have been planned as far back as last offseason.