The highest-impact signing of the 2017 offseason happened on March 31, more than three weeks after the frenzied opening of the NFL free-agent market. It was a little-noticed, one-year, $2 million contract by the Vikings for a backup quarterback who had lost the Rams' starting job to Jared Goff five months earlier.

Keep this in mind this March, when you're wailing, "When will my team sign somebody???"

We break down and analyze all of these moves as they happen, but the flaw in that kind of analysis is that none of us can see the future. What looks like good value in the moment can turn out to be a waste of money, while deals that don't make a ripple can turn out to be difference-makers.

Fortunately, we write this from 2018, with the benefit of hindsight. And with less than two months until the free-agent market opens again, we thought we'd take a look at the best and worst free-agent signings of 2017:

FIVE BEST

Deal: One year, $2 million

This deal barely got any coverage at the time. Having started half the 2016 season for the Rams before Goff took over, Keenum went to Minnesota to back up Sam Bradford in case Teddy Bridgewater wasn't healthy enough to start the season. Bradford lit it up in the season opener but got hurt, and the rest ... well, the rest is history. Keenum took over when Bridgewater was still on injured reserve, and while the team might have been planning to hand the job to Bridgewater when he got back, they were winning too much and Keenum was playing too well. So Keenum kept the job all year and now has the Vikings within a game of the Super Bowl. He hasn't been just a caretaker, either. Keenum finished the regular season with 3,547 passing yards, 22 touchdown passes to seven interceptions and ranked seventh in passer rating and second in the league in Total QBR. It suffices to say that Keenum's 2018 signing will attract more attention.

Deal: Four years, $60 million

The Jags paid a premium price for Campbell, guaranteeing $30 million in the first two years to hold off a late push from Campbell's hometown Broncos. But they got premium production for their money. Campbell finished second in the league with 14.5 sacks, forced three fumbles and returned one for a touchdown. He had four of the Jaguars' 10 sacks in a season-opening victory over Houston that announced the Jacksonville defense as a force that could dominate, and they're one of four teams that still have a chance to win it all.

Deal: One year, $9.5 million

Unable to get the long-term deal he sought at the outset of free agency, Jeffery effectively bet on himself and took the one-year deal with the Eagles. The deal came with an extra $4.5 million in incentives for Jeffery, who had a problem staying healthy during his time with the Chicago Bears. But the real payoff came in December, when Jeffery signed a four-year, $52.25 million extension with Philadelphia. The bet on himself worked out for him but also for the Eagles, as he caught nine touchdown passes in the regular season and helped lead them to the top seed in the NFC. As with the first two players on this list, Jeffery is playing for a conference championship this weekend.

Deal: Three years, $33.75 million

One of the things new Rams coach Sean McVay wanted to do to help Goff make strides in his second season was to shore up his protection. So the team made a big offer to the then-35-year-old Whitworth. They guaranteed him $15 million, including a $2.5 million roster bonus in 2018, to lure him out of Cincinnati. He helped solidify the line in front of Goff and Todd Gurley as the Rams raced to a surprise NFC West title.

Deal: Five years, $34 million

The summertime trade for fellow former Bills receiver Sammy Watkins got more attention than the signing of Woods. But while Watkins played the willing-decoy role in the Rams' offense all year, Woods busted out to the tune of 56 catches, 781 yards and five touchdowns. He emerged as Goff's primary deep threat and a trusted producer down the field. Woods turns 26 in April, and if he keeps producing the way he did in the second half of 2017, the Rams have a major bargain on their hands. He got $10 million fully guaranteed at signing, including his $3 million 2018 roster bonus. They'll pay him a $5 million salary in 2018, and he's got non-guaranteed salaries of $4.5 million for 2019, $5.5 million for 2020 and $7.5 million for 2021, though per-game roster bonuses could inflate those numbers up to $500,000 in each of the final three years.

Honorable mentions: A.J. Bouye, CB, Jacksonville Jaguars; Manti Te'o, LB, New Orleans Saints; Latavius Murray, RB, Minnesota Vikings; Micah Hyde, S, Buffalo Bills; Ted Ginn Jr., WR, New Orleans Saints; Marquise Goodwin, WR, San Francisco 49ers

Kenny Britt was a bust for the Browns. Scott W. Grau/Icon Sportswire

FIVE WORST

Deal: Three years, $45 million

This one, it feels like, we saw coming. The Bears guaranteed Glennon $18.5 million, including a $2.5 million 2018 roster bonus, to be their new starting quarterback before they knew they would draft Mitchell Trubisky. Glennon threw for 833 yards with four touchdowns to five interceptions and added three fumbles in four games before ceding the job to Trubisky. The Bears can get out of the deal this offseason if they want with only that $2.5 million guaranteed and a $4.5 million dead money charge. But if they do that, it'll be tough to say they got $18.5 million worth of production out of Glennon.

Deal: Four years, $32.5 million

The Browns let Terrelle Pryor Sr., who had success in Cleveland in 2016, leave and replaced him with Britt, who caught 18 passes (and dropped four) for 233 yards in nine games before they cut him and he finished the season as a Patriots reclamation project. The Browns gave Britt $10.5 million guaranteed, including a $6.5 million signing bonus and a $4 million fully guaranteed 2017 salary, for 18 catches. In related news, the Browns didn't win a game all season.

Deal: Three years, $21 million

Hey, they guaranteed Bennett only $6.3 million of it -- all signing bonus, all already paid. So the fact that he caught just 24 passes for 233 yards and no touchdowns before injuries set in and a controversial parting of ways landed him in New England and eventually on injured reserve didn't cost the Packers too much. But this was among the more disappointing pickups of the offseason. Bennett's signing certainly wasn't the main reason the Packers missed the playoffs for the first time in nine years -- we'll hang that on the Aaron Rodgers' injury. But he wasn't a helper while he was there.

Deal: One year, $7 million

Again, not a long-term budget-buster. But did the Seahawks have to guarantee $7 million to a former tackle who ended up ranked 53rd among guards by Pro Football Focus? The Joeckel signing was the 2017 offseason example of the Seahawks' tendency to see Band-Aid solutions on the offensive line -- a strategy that has backfired badly two years in a row. They ended up making a trade for left tackle Duane Brown during the season, perhaps signifying that they intend to change their approach.

Deal: Two years, $11 million

I'll be the first to admit I had this one wrong. I loved this signing for the Giants. I thought Marshall was just what they needed as a No. 2 wide receiver behind Odell Beckham Jr., and that they got Marshall at a good price since he didn't want to leave New York. (He was with the Jets before that.) But Marshall's signing was the first of about eleventy billion things to go wrong in one of the worst seasons in Giants history. They guaranteed him $5 million and got 18 catches, 154 yards and no touchdowns in four games before he went on injured reserve. It seems obvious that they'll move on.

Dishonorable mention: Terrelle Pryor Sr., WR, Washington; Eddie Lacy, RB, Seattle Seahawks; Adrian Peterson, RB, New Orleans Saints; Lawrence Timmons, LB, Miami Dolphins