LAKE FOREST, Ill. -- The Chicago Bears' offensive struggles over the past three years came despite pouring resources into that side of the ball.

Since the completion of the 2016 regular season, Chicago attempted to revamp its offense with a combination of high draft picks (quarterback Mitchell Trubisky, tight end Adam Shaheen, offensive lineman James Daniels, wide receiver Anthony Miller and running back David Montgomery), free-agent spending (quarterback Mike Glennon, tight end Dion Sims, wide receiver Markus Wheaton, wide receiver Allen Robinson, tight end Trey Burton, wide receiver Taylor Gabriel, wide receiver/returner Cordarrelle Patterson and running back Mike Davis) and the hiring of a forward-thinking, offensive-minded head coach (Matt Nagy).

The results haven't been favorable.

The Bears finished the 2019 season ranked near the bottom of the NFL in most team offensive categories.

Trubisky ended the season 28th in total QBR (39.4), tied for 27th in touchdown passes (17), 21st in passing yards (3,138), 32nd in yards gained per pass attempt (6.1) and 28th in traditional quarterback rating (83.0).

Patterson earned another trip to the Pro Bowl, but for special teams. On offense, Patterson contributed just 186 all-purpose yards. Robinson, on the other hand, played like an All-Pro, with 98 catches for 1,147 yards and seven touchdowns, but he was an anomaly on offense.

The next-most productive receiver was Miller (52-656-2) but he’s looking at a second consecutive offseason of rehab after undergoing another shoulder surgery. Tarik Cohen managed to catch 79 passes but for just 456 yards (5.8 yards per reception). Gabriel sustained multiple concussions over the course of the season. Burton was never healthy or productive. Montgomery flashed talent but Chicago never truly committed to running the football. And Shaheen is dangerously close to being a full-fledged bust.

So fixing the offense will again be an offseason priority. General manager Ryan Pace will no doubt use the draft to try to plug holes, but here’s a look at potential non-quarterback free agents who might help. As it currently stands, the Bears are projected to be in the bottom half of the league in available salary-cap space.

Atlanta Falcons tight end Austin Hooper, Los Angeles Chargers tight end Hunter Henry, Indianapolis Colts tight end Eric Ebron and Cincinnati Bengals tight end Tyler Eifert: Might as well put all the tight ends together. All four would be upgrades over what Chicago currently has at the position. Hooper and Henry will cost the most and could cost more than Pace can pay. Eifert is older (29) and Ebron spent the final few weeks of the 2019 season on injured reserve but both could help. Ebron had a career year in 2018 with 66 catches, and Eifert played under new Bears offensive coordinator Bill Lazor in Cincinnati.

Cincinnati Bengals wide receiver A.J. Green: Perhaps the lure of quarterback Joe Burrow is enough to keep Green in Cincinnati. The Bengals have already said they want to re-sign Green, who is coming off an ankle injury, but money talks. Again, the Bears don’t have a ton of cash to spend, so the notion of landing Green, Dallas’ Amari Cooper or San Francisco’s Emmanuel Sanders appears unlikely. But Chicago has a clear need at receiver. Robinson can’t be a one-man show again in 2020. The Bears have to give him some reliable help.

New England Patriots guard Joe Thuney: The 27-year-old is primarily a left guard but he’s versatile enough to line up almost anywhere on the offensive line. Thuney started every game for the Patriots since they drafted him in 2016 and is a two-time Super Bowl champion. Thuney and Washington’s Brandon Scherff will be the top two free-agent guards. The Bears are searching for permanent replacement for Kyle Long (retired) at right guard, and Pace is likely to take a long look at both of Chicago’s starting tackles (Charles Leno, Bobby Massie) in the offseason, too. Leno, the left tackle, is due $8 million in 2019 but is out of guaranteed money. Massie’s $6.9 million base salary for the upcoming season is fully guaranteed. The Bears' offensive line underwhelmed for a good portion of 2019. Part of that was because of scheme and part of that was because of the quarterback, but the unit will still be asked to perform much better in 2020. Signing the best available interior offensive lineman (even at significant cost) is something to consider.