Earlier Friday, we highlighted some of the Buffalo Bills' "rising" after three weeks of organized team activities (OTAs).

Now it's time to look at the other end of the spectrum: which players left something to be desired in OTAs? It's a harder question to answer, since the practices are voluntary, are not held in pads, and are geared towards installation -- not necessarily evaluation.

With that in mind, here are our notes on some players who didn't have as good a showing in OTAs as we would have expected:

EJ Manuel had an up-and-down performance during OTAs, particularly struggling with downfield throws. Kevin Hoffman/USA TODAY Sports

QB EJ Manuel: The Bills' chances this season start and end with Manuel. Naturally, that's going to put a spotlight on his every move in OTAs, minicamp, and eventually training camp. There were times over the past three weeks when Manuel showed poise. In Thursday's final OTA, Manuel looked calm and collected in pouring rain as he completed several throws in a row. On the other end, there were times when his performance wasn't ideal. One might expect a second-year quarterback to have a comfort level throwing downfield, but Manuel leaned heavily on dump-offs and scrambles in OTAs, saying afterward that he needed to take what the defense was giving him. That's smart, but only to a point. When the Bills needed to move the ball in two-minute drills, or needed to score a touchdown in red zone drills, his accuracy left something to be desired.

WR Sammy Watkins: Watkins might have been a victim of his own success in rookie camp. Those three days of practice last month consisted of positional drills and routes against air, and Watkins looked the part. His catch radius and precision with his footwork are unmatched by any other receiver on the roster. Yet as OTAs progressed, Watkins reminded us that he's still a rookie. The mental part of the game -- lining up after the huddle, reading defenses, etc. -- just wasn't at the same level as some of his teammates, who needed to direct Watkins to the right spot at times. Again, he's new, so that's not out of the ordinary. But if there was one red flag to be had from Watkins' OTAs, it was his drops this week. His final week of practice was his sloppiest from a pass-catching standpoint. The sticky mitts we saw in rookie camp and early in OTAs weren't there, although they could easily return in minicamp. We'll just have to wait and see.

On a side note, why would the NFLPA, the organization whose purpose is to represent and protect players, schedule their rookie premiere when teams were conducting OTAs? Watkins missed two of the Bills' nine OTAs because of that event, which includes a photo shoot for trading cards. Watkins should have been on the field learning the Bills' offense, and that's entirely the fault of the players' union, not him.

TE Scott Chandler: There are few players as well-spoken and respected as Chandler within the Bills' locker room. But the 6-foot-7 tight end, who will turn 29 in August, looked older than his age in OTAs. He's coming off knee surgery and was limited the first few days of OTAs as he continued to recover, but when he was on the field, he looked uncomfortable. Perhaps that will change once training camp rolls around. But not having drafted a tight end, the Bills need Chandler to be their top target at the position. After watching Chandler run on the practice field the past few weeks, I have questions if he's the right piece for what the Bills want in a fast-paced, athletic offense.

WR Mike Williams: When Williams arrived via trade in April, my first reaction was that he could be a top target in the Bills' offense. I'm less convinced now. Williams didn't stand out in OTAs and seeing him in action, there isn't a particular skill that he brings to the table that is different from the rest of the receiver group. If Watkins and Robert Woods become fixtures on the outside and Chris Hogan can continue to contribute in the slot, Williams starts to slide down the depth chart. The Bills will keep Marquise Goodwin and Marcus Easley on their final roster, so Williams will have to fight Hogan and T.J. Graham for the final spot. He could change my opinion in minicamp or early in training camp, but for right now I wouldn't call his spot on the team a sure bet.