Marshall Faulk asks: "When you're GMC Professional Grade, you perform at a high level day in and day out, whether you're being noticed or not. As we enter the latter part of the season, who is your team's unsung hero?"

An unsung hero is someone who flies under the radar — it's not the first person you think of when you think of the best players on a team, but it's the guy whose name eventually comes up in conversation, prompting everyone else to realize they've omitted a deserving player from their list.

For the 2014 Raiders, that player is left tackle Donald Penn.

In the 2014 Draft, five of the first 19 players selected were offensive tackles (including two of the first six). In 2013, that number was three of the top four picks and four of the top 11. The reason? Teams understand the value of protecting a quarterback, and they realize that the guy they have standing between JJ Watt, Justin Houston or Mario Williams and their franchise quarterback is a guy they want to trust.

For the Oakland Raiders, the trust hasn't always been there.

Up until this season, the Raiders were grooming Jared Veldheer to be their franchise left tackle, but after missing 11 games in the final year of his contract, the two parties couldn't reach an agreement on a new contract, allowing Veldheer to head to Arizona.

With a massive gap in their already depleted offensive line, the Raiders knew they would need to fill the hole with someone in free agency. Unfortunately, though, there simply wasn't much out there.

Then, they got a break. On March 13, the Tampa Bay Buccaneers released Donald Penn, a 31-year-old left tackle who hadn't missed a game since playing his first snap in 2007.

Knowing Penn filled a vacancy on their roster, Reggie McKenzie jumped at the chance to sign Penn, inking him to a 2-year, $9.6 million deal — one of the few veteran signings that has worked out for McKenzie this season.

Since coming to Oakland, Penn's durability has remained — starting all 10 games at left tackle for Oakland — and he has been an anchor on an offensive line that has been remarkably average on a roster that is far from it. In fact, the Raiders have allowed the fewest sacks of any offensive line in football this season.

Let that sink in for a second — the Oakland Raiders are the best in the league at something.

Okay, moving on.

A large part of that stat is Penn, who (according to ProFootballFocus.com) had allowed just one sack and one quarterback hit all year heading into Thursday's game. With numbers like that (and the fact that he has been penalized just once), it's no surprise that Penn is rated by PFF as the sixth-best pass-blocking left tackle and the 11th-best overall left tackle in the league.

Now, obviously a pass-blocking left tackle is important to any team, but I would argue that for a team with a rookie quarterback (that has almost no weapons around him), the ability to keep the QB upright is of the utmost importance. While Derek Carr has had his ups and downs this season, one reason he hasn't hit rock bottom is because the offensive line has limited the hits he has taken and the times he has been rushed into bad decisions.

And so, for that reason, I think the unsung hero of the Oakland Raiders is left tackle Donald Penn.

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