For a season that ended with a Super Bowl win, 2015 left a lot to be desired for the Denver Broncos, at least on the offensive side of the ball.

While the defense was the best in the league by our schedule-adjusted Net Expected Points (NEP) per play metric, the offense was nearly the opposite, ranking 28th (above four non-playoff teams, three of which picked in the top five of the NFL Draft).

For those new to NEP, it measures the value of each play on the field based on how an average team would be expected to perform in each scenario using historical data.

A lot of the disappointment came in the passing game. Peyton Manning was a shell of himself, but now he’s gone after walking off into the sunset after the Super Bowl. In between Manning’s stints was Brock Osweiler, who wasn’t much better, but he’s gone too after the Houston Texans gave him a boatload of money.

Perhaps the biggest disappointment on the offense, though, was wide receiver Demaryius Thomas. For the quarterback struggles, some of the issues were understandable. Manning was old. Osweiler was getting his first extended look and just might not be good. But Thomas had just signed a 5-year, $70-million contract extension in the offseason, which is a good sign a down year wasn’t expected by those directly involved.

Thomas didn’t exactly blame the deal for his struggles, but admitted the timing played some part in being uncomfortable during the season when he talked to SiriusXM NFL Radio earlier in the week:

“I think the main thing was sometimes thinking too much. I got my deal done, my mom got out. I was happy to be back with my team, but it was going out on the field, getting the timing down with the new offense. I wasn’t there for OTAs, I wasn’t there for minicamp. And then you had new routes. It was different for the quarterbacks because it was something Peyton had never done before, Brock had never done, either. So it was like some of the guys had more repetitions … and with me, it was coming back trying to get all my reps in training camp. I didn’t want to wear myself down, I wanted to be good for the team."

There are certainly points in there worth digging into.

Timing and Routes

One of the most interesting things Thomas noted was his lack of timing due to missing OTAs and minicamp. The Broncos shifted to a Gary Kubiak-led offense and, especially early on in the season, the Kubiak influence was heavy. After some timing issues were settled with Manning and a peak performance was given in Week 8, Thomas had to adjust to another quarterback two weeks later when Osweiler became the starter.

This shift led to some more awkward routes and targets, like this one from the Week 12 game against the New England Patriots. Thomas didn’t have a reception until late in the fourth quarter despite having 13 targets. While some were bad throws by Osweiler, others looked something like this:

Thomas breaks off his route, and it’s not exactly where Osweiler is expecting him to be -- the throw is wide and Thomas can’t bring it in. Had the two been on the same page, there was room for the receiver to turn up the field before the nearest defenders closed in. Thomas has the speed to do that and that type of catch and run is how he’s found much of his success.

While there’s a focus on the drops resulting from this -- Thomas did rack those up -- one of the biggest casualties of this issue was Thomas’s yards after catch (YAC). In the Manning era, Thomas has arguably been the league’s biggest receiving force after he gets the ball in his hands. But last season, he wasn’t in the same position to make those plays. Take a look at his YAC numbers over the past four seasons:

Thomas has ranked at least fourth in raw YAC in the previous three seasons. His percentage of receiving yards coming after the catch were also high -- almost half in 2013.

All of those numbers dropped in 2015. Maybe with another year in Kubiak’s system and a full offseason of workouts, Thomas’ timing and comfort in the offense will be better. But he’ll also have to adjust to a new quarterback, whoever that may be. That brings us to the quarterback play Thomas had last season.

Quarterback Play

Broncos quarterbacks weren’t good in 2015. That’s not much of a secret.

Manning ranked 35th out of 45 quarterbacks with at least 100 drop backs in Passing NEP per drop back. Osweiler was just slightly better at 25th. Despite the overall difference in production at the position, neither player really helped Thomas more on the field.

On an efficiency basis, Thomas was almost exactly the same player regardless of who was under center.

Thomas’ 0.60 Reception NEP per target ranked 26th among 32 receivers with at least 100 targets on the year. It was a drop from his 0.76 Reception NEP per target in 2014, which ranked 14th, and a steep drop from his 0.92 in 2013, which ranked fourth.

Even in his down year, Thomas was a highly-targeted receiver with 177 passes thrown his way. That’s usually going to hinder efficiency, especially when some targets are just uncatchable.

Or this pass against Minnesota when Thomas breaks in from the slot, finds a hole in the defense, but sees the ball sail by him and into the eagerly waiting arms of safety Harrison Smith. These were not uncommon sights last year in the Denver passing game.

Overall, it’s fair to view Thomas’s 2015 as a down year -- as much as a 105-catch, 1,304-yard season can be. There were certainly low points in the year that made the performance seem much worse than the raw stats would indicate. But it also might not be fair to take what happened last season as a sign for things to come in the future. The quarterback play might still be a question at this point in the offseason, but there's at least some reason to believe Thomas's part of the equation can be improved for 2016.