As Associated Press sports writer Dennis Waszak Jr. noted this week, the season has come full circle for Sam Darnold.

He was dealing with the beginning effects of mononucleosis the previous time he faced the Buffalo Bills in the New York Jets' season opener. The second-year quarterback was inconsistent in a 17-16 loss that was only the start of a stretch of bad news for Darnold.

He felt worse the day after the game, was diagnosed with the illness two days later and then missed three games because of it. It was a major factor in New York's early season struggles, a 1-7 start that only now are the Jets beginning to put behind them with a 5-2 closing run.

Too little, too late, of course. But Darnold and the Jets are no less motivated against the playoff-bound Bills to wrap up the season.

“It would be great to be able to go up against a really good Bills team, get a win — really good divisional win — away at the Bills," Darnold said. “So, it'd be huge to be able to go to a tough environment and win against a good team."

Especially if Darnold can finish the season with a solid performance.

“I think our offense has come a long way since then," he said of the previous time he faced the Bills. “I feel like I've come a long way. I thought just as a whole, we've gotten better. We've learned from our mistakes that we've made and again, that's what it's about. It's about continuing to get better. Obviously, there is a lot that we need to continue to improve every single week.

“This game is just another step, I think, in the right direction toward improvement."

Darnold will start his 13th game of the season Sunday at Buffalo, matching his appearances from last year as a rookie.

Based on the numbers alone, Darnold has been better this year and taken positive steps. He has 18 touchdown passes, 12 interceptions, a 61.7 percent completion rate and an 85.1 quarterback rating. Last year, Darnold had 17 TD throws, 15 INTs, a 57.7 percent completion rate and a 77.6 QB rating.

Adam Gase wasn't coaching Darnold last season, of course. But he has seen vast improvements from the spring to training camp — and even since that first game against Buffalo.

“He's seeing things that he might've saw earlier in the year and it looks cleaner to him now, it slows down," Gase said. “He knows what to do, he knows what his problems are, he knows what his outs are. ... It's pretty cool to kind of see how far everything has come since then."

The last five games in particular have stood out to Gase, starting with the Jets' 34-3 victory over Oakland on Nov. 24. It was that performance, during which Darnold threw for 315 yards and two touchdowns, that the coach thought the quarterback began seeing the game slower.

“Some things pre-snap looked really good, just communication-wise,” Gase said. “I think every game after that, you see improvement each week. Usually, when I see him talking at the line of scrimmage and he's moving fast and he's getting set and there's a lot of time left on the clock, that's when I feel like he's feeling really good."

Darnold has been solid down the stretch while facing some of the NFL's better defenses against Baltimore and Pittsburgh.

He'll get another chance to see how he measures up against Buffalo, which ranks No. 3 in overall defense.

In particular, Darnold will have to watch out for Bills' cornerback Tre'Davious White

White didn't shadow at all during the first half of the season, so he did not travel with Robby Anderson when these teams played in Week 1. Nonetheless, as ESPN's Mike Clay notes, Anderson struggled to four catches for 31 yards on eight targets in that game.

White has shadowed in six games since Week 9, so we can expect him to follow Anderson this week.

White shadowed Anderson twice during the 2017-18 seasons, with Anderson managing a 4-48-1 line on five targets in 2017 and a 4-76-1 line on seven targets in 2018.

Note that the Bills have nothing to play for this week, so it's possible White doesn't play the entire game. Beyond that, Anderson is questionable with a sore calf and might not be at full speed for this one.

Meanwhile, Le'Veon Bell drifted his way to 72 yards on 25 carries and 21 yards on four targets against the Steelers in Week 16. Bell has now reached 23 touches in back-to-back games and is averaging 20.1 touches per game this season, which includes at least 11 in all 13 outings.

As Clay suggested, the heavy usage is terrific, but Bell is averaging a horrific 3.3 yards per carry and shaky 5.8 yards per target, which has limited what could've been a much better fantasy campaign.

Bell has managed to finish as a top-10 fantasy back in 43 percent of his outings, which is sixth-best at the position, but Clay believes he's best viewed as an RB2 with some upside if key defenders are rested.