By Michael Hurley, CBS Boston

BOSTON (CBS) — It’s the NFL offseason. But is there really such a thing?

Between the ongoing Antonio Brown drama, coaching changes, mock drafts, fear of overweight free agents, speculation on surprise cuts, major quarterback trades and everything else that continues to play out on a daily basis, there’s not a whole lot of down time in today’s NFL.

And that’s fine. America’s No. 1 sport requires attention at all time. And the No. 1 team in America’s No. 1 sport obviously is not an exception.

With that in mind, and as rumors and ideas of Odell Beckham Jr. trades or free-agency strategies or contract restructures and offseason plans come into focus, it’s worth taking a look back before looking forward. In order to try to foresee and/or map out what Bill Belichick and Nick Caserio might do this upcoming offseason, it makes sense to look back at the past few offseasons to see which notable additions worked out and which ones didn’t.

So here’s a look at some of the more notable additions made by the Patriots over the past three seasons. (They’ve made the Super Bowl in the past three years, in case you’ve forgotten.) For the purpose of this exercise, we won’t count re-signings, and we won’t look at the draft. This is strictly a look at veteran players signed from outside the organization or brought in via trade before the season. It won’t be a complete list, as breaking down every last special teams signing or seventh lineman addition wouldn’t be the most productive exercise.

NOTABLE 2018 ADDITIONS

Adrian Clayborn

Grade: D

This was a bit of an odd signing from the jump. Clayborn was an experienced, seven-year NFL veteran, but he didn’t have much of a track record when it came to consistently getting to the quarterback. He was coming off a career-high 9.5-sack season, but six of those sacks (63 percent) came in one single game against Dallas. Outside of that one afternoon, Clayborn had 24 sacks in 80 career games.

Nevertheless, the Patriots gave Clayborn a two-year contract worth $10 million, with a $4 million signing bonus and $5.5 million of guarantees.

Clayborn failed to really make an impact, recording 2.5 sacks on the year. He never quite set the edge with consistency the way that the likes of James Harrison or Chris Long did before him, and he ended up as a healthy scratch for the final two regular-season games.

Clayborn did suit up for all three playoff games, registering a sack of Philip Rivers with 2:08 left in the fourth quarter of a 19-point game. He did record three QB hits that day, and one per game in the next two weeks, but again, he would not qualify as a major impact signing. He ended up taking just a tick over 30 percent of the team’s defensive snaps.

Though this hardly falls entirely on Clayborn’s shoulders, the Patriots as a team ranked third-to-last in sacks with just 30 on the year.

Danny Shelton

Grade: C

When the Patriots acquired Shelton (along with a fifth-round pick) from Cleveland in exchange for a third-round pick, it was seen as Classic Belichick — acquiring another team’s first-round pick and managing to get more out of that player than the team that drafted him. Belichick’s done that many times before; alas, that was not the case with Shelton.

The defensive tackle played 13 games, but he was a healthy scratch for the final three weeks of the regular season. He recorded just one tackle for a loss during the season and one quarterback hit, while registering 21 total tackles (10 solo). He was on the field for 31 percent of the Patriots’ defensive snaps on the year.

Shelton did start in the divisional round, though he played just seven snaps, and he was a healthy scratch in Kansas City for the AFC title game. He was active in the Super Bowl, and he came up with a tackle for a loss — forcing the Rams into a third-and-10 early in the second quarter. The Rams didn’t convert and had to punt.

Still, Shelton didn’t really do much to believe his stay in New England will last longer than a year.

Jeremy Hill

Grade: Incomplete

After letting Dion Lewis walk via free agency, the corresponding move — so to speak — was the signing of Jeremy Hill to a one-year, $1.5 million contract. Entering his fifth NFL season, Hill was expected to be given a stage to prove he was worth a much bigger contract from another team; the Patriots figured to be the beneficiary in the meantime.

But unfortunately for both parties, that arrangement lasted about 32 minutes, as Hill left the Patriots’ season opener on their first offensive snap of the second half with a torn ACL. His season was over after just four carries for 25 yards.

The Patriots nevertheless were able to maintain a top-five running game without Hill. That speaks to both the Patriots’ overall planning at running back and to the ability for rookie Sony Michel to step up in a big way. Considering how well they ran the ball — with an average of 162 yards per game in the postseason, and a total of nine rushing TDs in the playoffs — it would be hard to imagine Hill making it much better. But he might have proven to be quite helpful early in the year, when Michel was trying to return from a knee injury of his own, or in the middle of the year, when Cordarrelle Patterson was thrust into a lead back role.

Nevertheless, we can’t properly grade the Hill signing. It did look promising through the preseason, though.

Jason McCourty

Grade: A

The veteran cornerback’s season was not perfect from start to finish. Even he wasn’t sure if he’d survive the final roster cuts after playing quite a bit in the final preseason game. After taking just six snaps in the season opener, the present seemed just as murky as it had a week earlier.

From there, though, McCourty became a significant player on a Super Bowl-winning defense. He took 80 percent of the team’s defensive snaps — second-most among corners, behind only All-Pro Stephon Gilmore. (Jonathan Jones was the corner with the third-most snaps, though he took less than 50 percent.)

McCourty recorded one masterfully athletic interception, defended 10 passes, forced a fumble and made 70 total tackles.

And then of course in the Super Bowl, he made arguably the play of the game when he burst to the end zone to break up a would-be touchdown pass to a wide-open Brandin Cooks. McCourty was a tick late in recognizing the coverage bust, but he nevertheless made up for that with a spectacular play that was absolutely critical in the Super Bowl win.

Considering McCourty came to the Patriots almost for free (the Patriots sent a sixth-round pick to Cleveland and received McCourty and a seventh-round pick in return), it would hard to call this trade and acquisition anything but a wild success for the Patriots. (And that’s without even considering the Disney-esque storyline of twin brothers winning together.)

Cordarrelle Patterson

Grade: A

The Patriots signed Cordarrelle Patterson because they wanted a kick returner. They ended up getting a whole lot more.

Patterson certainly delivered on his main job description, ranking third in the NFL with a 28.8-yard average on his 23 kick returns. He took one back for a touchdown.

As a receiver — his technical job title — he was OK, catching 21 passes for 247 yards and three touchdowns. (He was also the recipient of Tom Brady’s best pass of the season.)

But it was as a rusher that Patterson really exceeded any and all expectations that could have been placed upon him. Entering the year, his single-season high for carries was 13. He ended up rushing the ball 42 times as a Patriot, averaging 5.4 yards per carry and finding the end zone once. That included a two-week stretch when Patterson became the lead back in Michel’s absence, rushing 21 combined times against the Bills and Packers and picking up 99 yards and a touchdown. Patterson’s ability to take handoffs out of the backfield proved incredibly important for the Patriots during that stretch.

All told, Patterson picked up 475 yards from scrimmage on a career-high 63 touches, while also being one of the best kick returners in the entire NFL.

Similar to McCourty, Patterson came on the cheap. The Patriots sent a fifth-round pick to Oakland in exchange for Patterson and a sixth-round pick. That low, low price ended up paying big dividends in a Super Bowl-winning season.

Trent Brown

Grade: A

There was legitimate panic in the streets last year when Nate Solder left. “Who will protect Tom Brady’s BLIND SIDE?!” the people yelled. It was terrible.

But there was no panic within the walls of 1 Patriot Place. Bill Belichick simply went out and acquired Trent Brown (and a fifth-round pick) from San Francisco in exchange for a third-round pick. Voila. Problem solved.

Of course, the Patriots did also invest major draft capital on the O-line with Isaiah Wynn, but Brown appeared to be the plan at left tackle all along. There, he was more than good enough to play a significant role in one of (if not the) best offensive lines in the NFL. The Patriots allowed just 21 sacks — third-fewest in the NFL — and they ranked fifth in rushing yards and tied for fourth in rushing touchdowns.

Brown was far from being an All-Pro or a Pro Bowler, but he was a Super Bowl champion, having played 97 percent of the team’s offensive snaps during the regular season and then 100 percent of the snaps in the playoffs. Brown is probably now heading off to make yachtloads of money elsewhere, but it would be difficult to quibble with the work he did in 2018.

Jordan Matthews

Grade: D-

It wasn’t an F, because of the low price paid to add the veteran receiver. But this one certainly didn’t work out, as the Patriots released Matthews after he had suffered a hamstring injury early in camp. The Patriots’ receiving situation being what it was, perhaps some patience in this case might have been prudent.

Then again, perhaps not. Matthews ended up playing 14 games with the Eagles, though he only caught 20 passes for 300 yards and two touchdowns. He did catch a 37-yard touchdown in the Eagles’ playoff loss in New Orleans.

Other Additions

The Patriots did sign offensive tackle Matt Tobin in the offseason, but he didn’t survive cut-down day. He was brought back midseason but was again released without having played a snap. … The Patriots tried to make Eric Decker work, but that experiment did not last long at all. … In terms of undrafed free agents, cornerback J.C. Jackson was a huge success. … In terms of re-signing their own players, the Patriots did well with Rex Burkhead and Matthew Slater.

OVERALL 2018 GRADE: B

It’s hard to argue with the results, and the team knocked it out of the park in the two key areas of left tackle and cornerback. But the best skill players for the champs came from the existing roster (Julian Edelman, James White, Rob Gronkowski), the draft (Sony Michel) and midseason trade (Josh Gordon). The best defensive players were also already on the roster. But the Patriots did enough in free agency/the trade market to bolster the roster enough to maintain a championship level of play.

Now, for the sake of expediting the process, here’s a quick-hit grading of the signings/additions made in the previous two seasons.

2017

Stephon Gilmore

Grade: A+

Lawrence Guy

Grade: A+

Rex Burkhead

Grade: C (but bonus points for going all Walter Payton in the 2018 AFC Championship Game)

Mike Gillislee

Grade: D-

David Harris

Grade: D-

2016

Chris Hogan

Grade: B

Chris Long

Grade: B+

Donald Brown

Grade: F

Shea McClellin

Grade: D

Terrance Knighton

Grade: F

UDFA Jonathan Jones

Grade: B+

You can email Michael Hurley or find him on Twitter @michaelFhurley.