In NFL free agency, it's important to exercise discretion when making moves. Sometimes the moves you don't make can be more significant than the ones you do. Even if your team needs an upgrade at a position, paying top dollar in an inflated market for a player can be costly. Years down the line, it is those big flops that hurt a franchise unable to rebuild as it lives out its impetuous mistake of trying to find a quick fix.
So which players come with a "buyer beware" tag in 2013? Here are the top 10 when viewed through the Pro Football Focus prism.
Note: More detailed explanations of the advanced statistics used below can be found here.
Defense
Cary Williams, cornerback
2012 team: Baltimore Ravens
Williams
If reports are to be believed, Williams bet on himself by turning down a three-year, $15 million contract from the Ravens last year. Two postseason interceptions, to go with four in the regular season (along with 11 pass deflections), might suggest that was a wise move from Williams.
But watching the tape a little closer doesn't leave you quite as impressed. Williams gave up 39 first downs in the regular season and six more in the postseason, meaning his combined 45 first downs surrendered were the second highest of all cornerbacks. He wasn't a shutdown corner but rather someone teams moved the chains on. He may be looking for top cornerback money, but teams shouldn't be fooled into thinking he is one.
LaRon Landry, safety
2012 team: New York Jets
Landry
On the back of what ended up being a Pro Bowl season, Landry has positioned himself to get paid. He won't be taking a hometown discount with the Jets because in his eyes his stock is at an all-time high after he proved he could handle the rigors of an NFL season by playing 96.6 percent of the Jets' defensive snaps.
Only the tape doesn't back up his performance. Eighty-eight tackles represent a big number, but his 4.7 run stop percentage was only 14th among safeties despite his spending 46.2 percent of his snaps in the box. He also got beat for 16 first downs and four touchdowns, the 11th-highest number of all safeties in coverage. Sure Landry can put a big hit on a receiver at times, but don't let those big plays fool you. He's not an elite, difference-making player, and he misses too many tackles (his 13 were 12th highest among safeties).
Osi Umenyiora, defensive end
2012 team: New York Giants
Umenyiora
Despite what Umenyiora may say, the tape definitely isn't kind to him after a 2012 where he looked a step slower and was a whole lot less productive.
The soon-to-be former Giant is above all else a pass-rusher, but his 8.6 pass rushing productivity score was down from 11.3 in 2011 -- and a large part of why he finished just 31st in our 4-3 defensive end rankings. A non-presence against the run for the most part, some team in desperate need of help in the pass rush may turn to him hoping to find answers, but the truth is he's better suited to a situational role with lowered expectations on his output.
Connor Barwin, outside linebacker
2012 team: Houston Texans
Barwin
This season was supposed to be the year that Barwin broke out. In theory it should have been, given that with teams paying extra attention to J.J. Watt, fewer resources were dedicated to stopping him. Only he couldn't take advantage of this, to the point where Houston can consider itself lucky to be priced out of his re-signing.
Barwin finished the season as our third-lowest-ranked 3-4 outside linebacker, struggling in all areas of the game. As a pass-rusher, he had the fourth-lowest score of his peers in our pass rushing productivity rating after notching 40 combined sacks, hits and hurries on 533 pass rushes, while in the run game, his run stop percentage score of 4.0 was the sixth-lowest number. You spend big money on impact players, and Barwin just isn't one of those.
Sean Smith, cornerback
2012 team: Miami Dolphins
Smith
There are times when I watch Smith and think he can be an elite cornerback; there are other times when I watch him and think he shouldn't even be on the field. For proof, no cornerback gave up more combined first downs and touchdowns than Smith's 46.
Smith started the season playing well but finished poorly, reminding us how badly he played in 2011 where he had the second-lowest coverage grade of all cornerbacks. Smith is as talented as he is inconsistent, and for that reason teams should be hesitant to part with the big bucks for him.
Rey Maualuga, linebacker
2012 team: Cincinnati Bengals
Maualuga
Granted, no team thinks it's going to be getting a superstar linebacker with Maualuga, but it might think it has found itself a stopgap starter and pay him as such.
And it would be wrong to do so.
Maualuga was our lowest-ranked middle linebacker this season, struggling all over the field but being a particular liability in coverage (London Fletcher was the only linebacker to give up more than Maualuga's 37 combined first downs and touchdowns). Throw in 16 missed tackles -- fifth most among inside linebackers -- and you have a liability on your hands.
Offense
Dustin Keller, tight end
2012 team: Jets
Keller
If you were building an ideal tight end, he'd probably look a lot like Keller: explosive and able to do damage with the ball in his hands.
Yet all too often he's not a mismatch, and with the way he blocks, ensuring the Jets can't use him as an every-down tight end, he really needs to be more of a playmaker in the receiving game. This season he picked up only 1.48 yards per route run, a number that if he had run enough routes to qualify would have ranked tied for 15th with Martellus Bennett, a much more complete player.
Keller is capable, but there's too much inconsistency in his game for him to be relied upon and given big money.
Jake Long, left tackle
2012 team: Dolphins
Long
There's a lot to be said for the position of left tackle being less important now, with teams getting rid of the ball quicker and quarterbacks defined by how they handle pressure. For example, has Joe Thomas propelled to Cleveland Browns to victory?
Even if you don't share that viewpoint, you would be hard-pressed not to see a depressing trend in Long's recent play. In his first three years in the league he was exceptional, but whether it's injuries or wear and tear, his past two years have created more questions, to the point where investing big money in him is a true gamble. If you judge a left tackle by his work in pass protection, Long has gone from ranking first in our pass blocking efficiency stat in 2009 and 2010 to 13th (2011) and what would have been 14th (2012) if he had have played enough snaps to qualify.
Is that the kind of recent performance a team should put a substantial part of its salary cap into, in the hope he turns it around?
Reggie Bush, running back
2012 team: Dolphins
Bush
Bush was 14 yards away from a second consecutive 1,000-yard season, but despite his high profile and success in Miami, there isn't much reason to invest significant money in him.
Out of 59 running backs to play at least 200 snaps, Bush finished 31st in our rankings, and that was mostly due to his receiving skills. For Bush, the same old problems prevail, as he averaged just 2.06 yards after contact per carry, a number that was better than only five backs with more than 100 carries. He just isn't a convincing runner between the tackles, teasing us with the idea he will be and then being quick to bounce the ball outside.
The truth is that the New Orleans Saints used him the way they did because that was the best use of his talents. Now he is older and has less tread on the tires.
Donnie Avery, wide receiver
2012 team: Indianapolis Colts
Avery
Given how obsessed Andrew Luck was with Reggie Wayne at times (179 balls thrown his way), it might be a minor miracle for some that Avery was able to walk away with 781 yards. That's a decent number for a No. 2 receiver.
But Avery benefited from a pass-happy offense in which Bruce Arians at times seemed determined to treat him as he had Mike Wallace in Pittsburgh. It meant the former Ram was targeted 25 times on balls aimed over 20 yards in the air (13th highest in the league), yet he caught only six of them while dropping four.
Indeed, drops were a huge problem for the unreliable Avery, as he led our drop rate signature stat for wideouts after dropping 12 of 72 catchable balls. A team might think he can provide another dimension to its offense, but it will overspend on plays left on the field.