The pitfalls of free agency are well known at this point. Winning headlines in March doesn’t guarantee that a team will win games in December, and every year fresh signings are accompanied by the release of players with big-money contracts who didn’t pan out (the bones of this free-agency graveyard reside mostly in Jacksonville).

Free agency undeniably has its benefits, though. Chief among them is the chance to remove uncertainty from roster construction. Filling a need with a high draft pick might be a franchise’s most prudent move, but considering rookie hit rates, the inherent risk is obvious. The upshot to signing a proven commodity is that it provides teams with a sense of comfort. Even if a front office pays full market price for a player, it can usually feel good about its chances of upgrading a key spot.

With most of the 2017 free-agent class having signed, now is a good time to assess which teams made the biggest upgrades, from positions that were black holes in the 2016 season to ones that could be difference-makers this fall. Not all of these signings involved superstars, but all could prove incredibly impactful once games kick off.

Alshon Jeffery, WR, Eagles

It’d be tough to identify a weaker NFL position group than Philadelphia’s wide receivers last season. Slot man Jordan Matthews played the nominal role of the Eagles no. 1 guy, and while that was problematic in its own right, the crew surrounding him was even more worrisome. Nelson Agholor, who was a healthy scratch in a Week 12 loss to Green Bay on Monday Night Football, was on the field more than any other Philly receiver over the course of the season (77.9 percent of the offensive snaps). That worked out about as well as anyone could have expected.

The lack of receiving talent forced head coach Doug Pederson to get creative in how he spread the ball around (tight end Zach Ertz led the roster with 78 catches despite missing two games to injury, and the immortal Darren Sproles finished third on the team with 52 receptions), and it prompted general manager Howie Roseman to send a message during free agency. The franchise knows Carson Wentz needs legitimate options on the outside to further his development. Enter Alshon Jeffery.

At his best (and healthiest), Jeffery is exactly the type of receiver the Eagles lacked in the 2016 campaign. A contested-catch master who makes plays even when he’s not open, the 6-foot-3 218-pounder gives Wentz a massive target down the field that could help mask any growing pains the second-year quarterback experiences.

Jeffery’s ability has never been at issue. The problem for the former Bears receiver has been avoiding injury. Hamstring and lower-body issues have plagued him since his 2012 rookie season, robbing him of 13 career games and limiting his effectiveness when he was on the field. Given the numbers of his new deal, though, the Eagles’ potential rewards outweigh the risk.

Jeffery agreed to a one-year contract that guaranteed him only $9.5 million at signing, with another $4.5 million tied to incentives for yards, catches, games played, and a Pro Bowl invitation. That’s a no-brainer for Philly. If Jeffery earns every dime of his potential $14 million, he’d still make less than the 2017 receiver franchise tag ($15.7 million). The Eagles’ addition of Torrey Smith will give this offense a speed element it lacked in Wentz’s rookie season, but Jeffery’s signing was the transformative move — and the one that could significantly impact Wentz’s development in Year 2.

John Simon and Jabaal Sheard, Edge Rushers, Colts

Indianapolis didn’t have a choice but to revamp its pass rush this offseason. Franchise stalwart Robert Mathis is now retired, available to spend his time trying to woo Donna Meagle, and Erik Walden is currently a free agent.

That left new GM Chris Ballard with a glaring need, and he responded by picking up two solid edge defenders from AFC playoff teams. Jabaal Sheard has been a useful pass rusher throughout his entire career, and while his numbers in New England were never staggering, he’s a consistent presence and somehow just 27 years old. His deal with the Colts is worth $25 million over three years, with only $9.5 million guaranteed at signing. That could prove to be great value at a spot where Indy was desperate.

Sheard is a relatively known quantity, making Ballard’s other signing — former Texans backup John Simon — the more intriguing of the two. Simon notched 3.5 sacks in 11 games in 2016, occasionally jumping off the screen in his second season as a regular part of Houston’s rotation, even while surrounded by the Texans stars in the front four. The challenge for Simon will be moving from a defense in which he was the third pass-rush option (behind Whitney Mercilus and Jadeveon Clowney) to a Colts unit that will make him the focal point of protection schemes. He has shown enough to indicate he’s ready to make the jump, but this is one of the constant concerns in free agency — whether bit players in one setting can transition to be foundational pieces in another.

Fortunately for Indy, the price it had to pay for Simon was more than reasonable. Only the first year of his deal ($5.5 million) is guaranteed, and the Colts will be able to keep him for a combined $7.5 million over the next two seasons if they desire. That’s a bargain for any player who can even sort of bother opposing quarterbacks. Ballard’s biggest task in his first offseason was trying to remake a defense that ranked 29th in Football Outsiders’ DVOA; both of these deals should help address that.

Andrew Whitworth, LT, Rams

I’ve already written about all the money shelled out to offensive linemen in this free-agency period, but there’s no way to properly make this list without including Whitworth. Los Angeles’s deal for the 35-year-old former Bengals tackle is the perfect example of a team using free agency to escape the reality it’s known at a position for far too long.

For years, left tackle has been a merciless, unrelenting wasteland for the Rams. Over the course of the past eight seasons, the franchise has used the no. 2 overall pick on two players at the position — Jason Smith in 2009 and Greg Robinson in 2014 — and both times it ended horribly. Smith eventually shuffled to the right side, replaced by the woefully out of position Rodger Saffold (who now plays left guard). And after Robinson spent the past two seasons on the outside, it seems like the Rams have seen enough.

Robinson will move inside to guard this year in an effort to salvage his career and to prevent the Rams from lighting yet another top-five pick on fire. In his place, L.A. will turn to one of the more reliable players at any position over the past decade. Whitworth had long been a fixture on Cincinnati’s left side, and even as he hit his mid-30s, his play didn’t fall off much. It might seem odd for a team with as many needs as the Rams to lock up a player toward the tail end of his career, but there’s logic behind the move. By plugging in Whitworth, the franchise’s hope is that the group up front will give quarterback Jared Goff a fighting chance to succeed.

For the first time in years, the Rams left tackle spot has gone from terrifyingly unknown to stable. That brings them one step closer to getting Goff where he needs to go.

Dontari Poe, NT, Falcons

The market for the 26-year-old nose tackle, who went 11th overall in the 2012 draft, was substantially colder than most people imagined it would be. Atlanta became the beneficiary, inking Poe to a one-year, $8 million deal.

For Poe, this contract offers a chance to show that his recent lackluster production is the outlier relative to the big seasons he enjoyed in 2013 and 2014, when he had 10.5 combined sacks and made his influence felt against the run. The second part of that is what the Falcons hope to squeeze out of their new man in the middle. Atlanta’s young defense came into its own as a pass-defending unit down the stretch thanks to contributions from many first- and second-year players, but over the second half of the season head coach Dan Quinn’s defense finished dead last in run defense DVOA.

Poe, at his best, should help change that. The Falcons have already made it known that they want his playing weight at 330 pounds (down 10 pounds from where he was last season), and even in a slimmed-down state, Poe would give them a presence unlike any on the roster. Grady Jarrett is an ascending three-technique penetrator, but like many players on Atlanta’s defense, much of his value is derived from speed rather than bulk. Instead of having to rely on the undersized and miscast collection of Ra’Shede Hageman and (the recently departed) Jonathan Babineaux, Quinn now has a prototypical nose tackle to really bring this group together.

Logan Ryan, CB, Titans

Any time that a team releases a player who started the previous day, things probably aren’t going too well. That’s what happened following Tennessee’s 27–21 win over the Bears in Week 12, after which the Titans cut cornerback Perrish Cox for his part in allowing Matt Barkley to record a 316-yard, three-touchdown performance.

Corner was clearly Tennessee’s biggest defensive need coming into this offseason, and the Titans filled it by handing former Patriots cover man Logan Ryan a three-year, $30 million contract with $12 million guaranteed at signing. That’s a sizable deal for a player who was never considered a no. 1 corner in New England, but Ryan played well enough down the stretch last fall to warrant this type of consideration. A smart, versatile player who can line up inside and outside, Ryan gives the Titans both an upgrade and flexibility in their secondary.

By signing Ryan (and run-stuffing strong safety Johnathan Cyprien), Tennessee made a concerted effort to transform its secondary into a group that doesn’t detract from the efforts of the team’s talented front four. With the excellent Jurrell Casey inside and the combination of Derrick Morgan and Brian Orakpo (19.5 combined sacks in 2016) outside, the Titans are loaded along the line. If Ryan and Cyprien can successfully patrol the defensive backfield, there’s a chance a unit that finished 24th in defensive DVOA can take some people by surprise in 2017.

Prince Amukamara, CB, Bears

The Bears entered the offseason in a similar spot to the Titans. Chicago’s front seven was ravaged by injuries last year, but with a group that includes Akiem Hicks, Pernell McPhee, and 2016 first-round pick Leonard Floyd, it has the potential to unleash combinations that could get exciting in a hurry.

On paper, the Bears’ pass-rushing talent and the duo of Danny Trevathan and Jerrell Freeman at inside linebacker are enough to create some (potentially heartbreaking) optimism about coordinator Vic Fangio’s defense. The problem is that for as good as the front seven looked last fall, the secondary looked even worse. With 2014 first-round pick Kyle Fuller on the shelf for the entire campaign, the Bears were forced to rely on 30-year-old Tracy Porter, waiver claim CreVon LeBlanc, and Bryce Callahan at cornerback. Coming into free agency, the outlook for 2017 wasn’t much better. Fuller’s future with the club is uncertain, prompting question marks at both corner spots.

General manager Ryan Pace’s strategy was reportedly to throw huge money at the players near the top of the market, including Stephon Gilmore (who signed with New England) and A.J. Bouye (who signed with Jacksonville). With those options gone, the Bears elected to ink former Giants and Jaguars corner Prince Amukamara to a one-year, $7 million deal (as well as former Arizona cornerback Marcus Cooper to what amounts to a one-year, $6 million contract with team control after that).

Amukamara may not be the prize that Gilmore or Bouye represents, but he remains a steady, NFL-caliber corner — something that Chicago lacked last season. Fans will never sing in the streets over this type of signing, but it could pay major dividends in a few months. In free agency, sometimes what matters is just getting a little better than you were before.