Allen had one year remaining on his rookie contract. That has been thrown out, so he's signed through 2018.
Allen, the team's fourth-round draft pick in 2011, was expected to sign a deal this off-season, and they waited until the 11th hour to strike a deal that was nearly identical to the one given to Keenan Lewis by the New Orleans Saints.
Lewis, who had a big year in New Orleans after having left the Steelers last season, signed a five-year, $26.3 million deal before the 2013 season. The Steelers' salary cap position was far different at the time than it is now - they are projected to be around $11 million under the cap heading into this season.
The team had the ability to not overpay for Lewis because of the development they saw at the end of the 2012 season from Allen - a player defensive coordinator Dick LeBeau thought, before the season, was almost even with Lewis in terms of ability. Lewis had a breakout year in 2012 for the Steelers, but Allen didn't quite match him last season, his first as a starter.
Allen, the 2012 and 2013 winner of the Jersey Rules championship, didn't quite live up to the hype last season, notching 51 tackles and two interceptions. In five quarters of play between Weeks 16 and 17 in 2012, Allen forced five turnovers, which was more than Lewis had in his previous three seasons in the NFL combined.
That led to the belief the Steelers - cap-strapped at the time - could keep Allen on his rising development curve by giving him a starting job in his third NFL season and sign veteran and ex-Steelers CB William Gay to handle the slot duties at a fraction of the price of Lewis. The move was met with skepticism and doubters appear to have gotten the better of that argument in the short term. But the deck is stacked a bit, considering the Steelers simply didn't have the cap space in 2013 to sign Lewis to the deal New Orleans gave him.
But Allen is no longer a rising player on a rookie deal. He'll assume the expectations of becoming the only Steelers player not named Ike Taylor in over a decade to sign an extension with the team on top of his rookie deal (Gay left and came back). For a franchise that typically hasn't spent much on cornerbacks, Allen's deal is particularly impressive.
The 2014 season starts Sunday, and Allen will start opposite Ike Taylor for the second consecutive season. The last time the Steelers signed a defensive player to an extension the night before their first game was in 2011. And the Steelers, with Troy Polamalu's new contract in hand, went out to lose the opener 34-7 to Baltimore.