Undrafted NFL Free Agents 2012: Power Ranking the Best Post-Draft Signings

Making smart signings after the draft can take an otherwise average rookie class and make it a good one. After all, there isn't much difference between a seventh-round pick and an undrafted free agent. So players signed after the draft ends shouldn't be overlooked.

Let's take a look at the best post-draft signings so far based on the player's ability to become a value piece down the line. All agreements according to Pro Football Weekly.

1. Gerell Robinson—Denver Broncos

The Broncos didn't draft a wide receiver, despite plenty of question marks behind Demaryius Thomas and Eric Decker. That gives Robinson a chance to earn some playing time if he can outshine some of the veterans on the roster, which won't really be a difficult task.

Robinson's biggest key will be developing a relationship with new Broncos quarterback Peyton Manning. The legendary QB has made far less talented receivers into big-time stars—look no further than Brandon Stokley—so Robinson would thrive if he can break the lineup.

He doesn't have elite speed, but he has prototypical size and has no problem going into tough areas to make catches. Any wide receiver who's willing to do that will find a niche.

2. Case Keenum—Houston Texans

Matt Schaub has missed at least five games three times since joining the Texans in 2007, so it doesn't hurt for Houston to have an extra option available. Keenum posted monster numbers in college, but fell because nobody is sure how his game will translate to the next level.

Even though his below-average size and moderate arm strength limit his upside, he's a nice backup option due to his accuracy and intelligence. Keenum is the type of player where the coaches can tell him to simply not lose the game, and he'll make enough plays to keep the Texans alive.

You don't throw 155 touchdowns at the college level without a great understanding of the game and a high skill level. Keenum may never become a full-time starter, but he'll be a valuable second or third QB.

3. Marquis Maze—Pittsburgh Steelers

Maze flew under the radar because he never posted monster numbers at Alabama. The main reason for that isn't a lack of still, though, but rather a run-first offense that had several elite running backs leading the way.

He reminds me a lot of Wes Welker in terms of being a wideout of smaller stature who should be able to expose holes in a defense simply by finding the soft spot in the secondary. No single skill makes him stand out, but that doesn't make it impossible to be a playmaker, as Welker has shown.

Between Mike Wallace and Antonio Brown, the Steelers have the outside deep threats covered. Maze should emerge as a slot target during training camp.