Last offseason, New York Giants General Manager Jerry Reese had a well-defined mission. Fix a broken defense.

We know now, of course, that his effort to do that turned out better than anyone could have expected. Free agent mega-contracts for Damon Harrison, Olivier Vernon and Janoris Jenkins, re-signing Jason Pierre-Paul, adding lesser free agents like Keenan Robinson, Kelvin Sheppard and Leon Hall, and using a first-round pick on cornerback Eli Apple infused the defense with talent and leadership it didn’t have in 2015. The result was a group that ended up second in the league in points allowed.

There will, naturally, still be decisions the Giants need to make on the defensive side of the ball. Can they fit free-agent contracts for both Jason Pierre-Paul and Johnathan Hankins under the salary cap? Will they keep Dominique Rodgers-Cromartie? Do they need to add an edge rusher or a linebacker? Is B.J. Goodson the middle linebacker of the future?

Still, like last offseason, Reese has one obvious and not-so-simple task this offseason.

Fix the offense!

Reese has often said over the past two or three seasons that in the modern NFL you need to score 28 points to win consistently. The Giants just finished a season during which they went 11-5 (11-6 including the playoff loss), yet they didn’t reach the 28-point barrier a single time. In fact, in the 17 games the Giants played, they failed to reach the 20-point mark in 10 games.

The fact that they won 11 games with that sort of poor production from the offense is a testament to how good the defense was. It is, however, something that has to change if the Giants are going to be a true championship contender next season.

Let’s use today’s “Five things I think I think” about the Giants to look at five things the Giants must address to improve on offense next season.

Upgrade the offensive line

Bring up this topic and the first thing everyone thinks about is “get Ereck Flowers out of the left tackle spot.” Yes, whether or not Flowers will be the Giants’ left tackle in 2017 is something the organization needs to seriously discuss, and Reese admitted Monday that they will. The Giants’ offensive line issues, though, go beyond the struggling to improve 2015 first-round pick.

The Giants are unsettled at three spots — left tackle, right guard and right tackle. The Giants need to start by figuring out which of those spots Flowers will play, a decision that might depend on whether or not they can find an upgrade at left tackle this offseason, and go from there.

Veteran right guard John Jerry is a free agent. Do the Giants want to retain him, or move on? He is an adequate player, but my guess is they move on. It doesn’t appear they believe Bobby Hart is the answer at right tackle, otherwise he would have been playing Sunday vs. Green Bay.

Eli Manning is 36 and his window is closing. The Giants need to fix the offensive line, to both pass and run-block better, to take advantage of the time he has left.

Get a real outside wide receiver

The Giants have a decision to make about the future of Victor Cruz, who carries a $9.4 million cap hit next season. Simply put, there is no way the Giants can pay the 30-year-old Cruz that much next season. He just isn’t good enough anymore, having caught only 39 passes and lost playing time to first Roger Lewis Jr. and then Tavarres King. With smallish receivers in Odell Beckham Jr. and Sterling Shepard ahead of him his skillset is really redundant in the Giants’ three-wide receiver set. Pushing sentimentality aside, my vote is for the Giants to move on.

The Giants could use someone with a different build, a different skill set. They could use a big-bodied outside wide receiver. “Invictus” suggested Brian Quick in free agency. I don’t know if Quick, another free agent, or a draft pick is the answer. I do know the Giants need to look for a solution.

Get better at tight end

One 51-yard catch in a playoff game does not make Will Tye the answer at tight end. Tye’s production, 48 catches, one TD, 8.0 yards per catch in a full 2015 season was a significant drop after he caught 36 passes, three for touchdowns, over the final nine games of 2015.

The Giants need a pass-receiving tight end who can consistently threaten the seam and be a red zone threat. They also need better, more consistent blocking from this position. Maybe veteran H-Back Will Johnson, who spent the year on IR, will help. If the Giants bring him back. Maybe Jerell Adams will develop. The Giants need a player at this position who is a real weapon, not just a guy they use as a bail-out when Manning is pressured or blitzed.

Draft analysts indicate that there are a plethora of tight ends worthy of Day 1 or Day 2 selections. I would be surprised if the Giants don’t use an early pick to try and find an answer, at least to the pass-catching portion, for this issue.

Figure out the play-calling/offensive philosophy

Ben McAdoo and his over-sized play card became the source of a lot of commentary as the Giants’ offense struggled, some of it humorous, some biting. McAdoo’s ridiculous-looking play card became symbolic for an offense that was out of whack all season. Like the play card, it never looked right. And there was really nothing funny about it.

Maybe McAdoo should give up the play-calling, maybe he shouldn’t. I really don’t know. That is something he and the organization need to have a long, truthful conversation about this offseason.

What I do know is that the personnel isn’t the only thing the Giants need to look at this offseason. How they approach the offense as a whole needs to be looked at.

Let’s face it, Cover 2/Tampa 2 is a defensive philosophy NFL offenses figured out how to exploit years ago. It is troubling that the Giants couldn’t figure out how to attack it, and every time they saw it just said “well, teams aren’t letting us do what we want to do.”

That’s not good enough.

The Giants stubbornly stayed in “11” personnel with three wide receivers roughly 90 percent of the time this season when league average is about 60 percent. They changed some of the players they used, but never really changed what they tried to do, more or less just giving in to how teams played them. No matter what you think your best personnel grouping is, there has to be more flexibility than that.

The Giants almost never used four wide receivers. They had some success using two tight ends, but rarely stuck with it even when it showed signs of working. The 51-yard pass to Will Tye Sunday might have been the first time all season the Giants attacked the seam down the field with a tight end. Manning was a master of play-action passing from under center when Kevin Gilbride was offensive coordinator. It’s something the Giants barely incorporate now.

Speaking of Gilbride, Mike Sullivan is a terrific coach and better person, but he learned offense from Gilbride. He shouldn’t be a fall guy for the offense’s failings, but if he isn’t the right guy to implement what McAdoo wants then a change needs to be considered.

McAdoo was a rookie head coach who won 11 games, and he deserves credit for that. But, this was the offense he built and he chose to continue calling plays. He needs to take a hit for its short-comings, and look in the mirror. I believe what he will see, if he’s honest, is that his own choices were part of what held the offense back.

Decide what to do at running back

Is Paul Perkins the “bell cow” featured back of the future? Is Perkins, who gained 456 yards on 112 carries as a rookie (4.1 yards per carry) better-suited to being part of a rotation? That’s where the decision-making has to start in the Giants’ backfield.

My guess is, the backfield looks vastly different in 2017 than it did this season.

Rashad Jennings turns 32 in March. He carries a $3.062 million cap hit next season, and the Giants can save roughly $2.5 million by cutting him. My guess is that the re-structuring of the backfield will start by doing exactly that.

I don’t see any reason the Giants would bring back Bobby Rainey. They could easily part with the oft-injured and under-utilized Orleans Darkwa.

That would leave only Perkins and third-down specialist Shane Vereen. Would the Giants do a complete tear-down and part with Vereen? He carries a $4.9 million cap hit next season. The Giants could save roughly $3.75 million against the cap by letting him go. If they believe Perkins can handle the pass-catching duties would they consider Vereen expendable? Perhaps, especially if it helps them keep Hankins and Pierre-Paul.