LATROBE, Pa. -- The NFL is crawling with excellent wide receiver prospects. Just about every team has one. Some teams have two or three. The Steelers-Bills joint practices are downright lousy with them.

Some of the new receivers are huge. Some possess Olympic-level speed. A few combine size and speed into an irresistible and seemingly un-coverable package. The rookies are poised to take the league by storm. Just maybe not this year.

The rookie wide receiver class of 2014 is poised to be the best since 1996, when Marvin Harrison, Terrell Owens, Keyshawn Johnson, Eric Moulds, Amani Toomer, Terry Glenn, Joe Horn and others entered the league. But expectations may be getting too high, too fast. The Bills are trying to tamp down Rookie of the Year talk for Sammy Watkins that started the day camp opened. Chip Kelly would rather huddle for a month than relent and promote Jordan Matthews to the first string, though Matthews has nothing else to learn from beating backup cornerbacks and catching passes from Mark Sanchez. The Cardinals are taking a different approach: general manager Steve Keim compared Josh Brown to Anquan Boldin, the Arizona football equivalent of calling a kid with an acoustic guitar the next Dylan.

As for the Steelers, they insist on throwing ice water over any excitement about king-sized fourth-round pick Martavis Bryant or third round receiver-rusher-returner-speedster Dri Archer.

"I'm not going to jump on any bandwagon yet," Ben Roethlisberger said when asked about Bryant.

"Two steps forward, one step back, and so forth," head coach Mike Tomlin said of the development of his young receivers.

So much for "Offensive Rookie of the Year" or "Next Anquan Boldin."

Wednesday's joint practices, like those lukewarm soundbites, tempered enthusiasm for the Steelers rookie receiving weapons without crushing it. Veteran receivers Emmanuel Sanders and Jerricho Cotchery left via free agency, opening the door for size-speed prospect Bryant, Combine sprint champion Archer, and second-year project Markus Wheaton. For an offense that sputtered whenever Ben Roethlisberger wasn't throwing to Antonio Brown, the bigger, faster weapons are welcome additions. They just may not pay major dividends immediately.

Working against unfamiliar Bills cornerbacks, Bryant hauled in several deep passes along the sidelines in one-on-one and full-squad drills. His size, long arms and longer strides gave him a clear edge against tiny Bills second-string cornerbacks: He could reach above and beyond his defender's grasp to make contested catches. But then Bryant ran a simple hook route in a 7-on-7 drill, put his hands out for a short catch, and let the ball ricochet of his palms.

Archer -- who ran the second-fastest 40-yard dash in Scouting Combine history in February (4.26 seconds; Chris Johnson has him beat by less than a heartbeat) -- saw limited snaps in Wednesday's joint practices. Archer runs drills with the running backs, but he is not strictly the third running back or the fourth or fifth receiver. He's a package player who flashes onto and off the field as a split end, back and motion player, but mostly fields punts and takes pass-protection reps. Given a shotgun sweep to display his wheels, Archer was swiftly tackled in the backfield by Bills defenders.

On the opposite field, Watkins dropped several passes against the Steelers defense after blurring past his cornerback for a highlight-worthy catch at the start of practice. Watkins, the fourth player taken in this year's draft, comes with more polish and higher expectations than Bryant (his teammate at Clemson) or Archer. "He's very mature," Bills coach Doug Marrone said of Watkins on Wednesday. "He's probably going into this like a seasoned veteran … He's not wide-eyed or anything." Still, the practice-field miscues reveal that Watkins has as much to learn as any rookie.

The joint practices were microcosms of an up-and-down preseason for the rookies. Bryant had a miserable exhibition debut for the Steelers. He dropped a pass, muffed a punt and fumbled after a reception against the Giants. Archer made the highlight reel with a 46-yard screen and run with the starters, but he played just five offensive snaps: fewer that Roethlisberger. Watkins provides a YouTube-worthy practice highlight per day, but he has caught just three passes for 21 yards in two preseason games for a mostly-moribund Bills first-unit offense.

There is clearly some learning to be done, particularly for Bryant, who had a chance to overtake Wheaton for the Steelers starting job but has been unable to get anyone on his bandwagon. "I'm looking for him to grow in all areas and have the type of detail in his work where we can rely upon him," Tomlin said of Bryant. "Like a lot of young guys he's moving toward that. He's not at a quick enough pace for us, not a quick enough pace for him, so we'll continue to work."

Even that ugly preseason performance was not a total loss for Bryant, who drew two pass interference penalties. "He has the speed you can't coach, the size you can't coach," receiver coach Richard Mann said earlier in the week. Bryant was only a one-year starter on a Clemson offense that featured both Watkins and DeAndre Hopkins, a first-round pick by the Texans in 2012. "What we've got to do is get him honed in, teach him how to do things," Mann said. "He's doing pretty good as far as learning it and having recall. He's just not doing it quite right all of the time."

Archer also has speed that cannot be coached and raw talent that must be honed. He was the fastest player on either side of the ball by at least a step in most Kent State games, so his coaches tied the offense in knots getting him the ball. Archer was often miscast as a 175-pound between-the-tackles rusher, as it made more sense to just feed him the football on handoffs than to fiddle with options or screens. Archer produced results -- 7.2 yards per carry in a career against mid major competition -- but he also lost most of his senior season to ankle injuries. The Steelers are letting Archer concentrate on "instinct" plays like punt returns and end-arounds. The rest of his game, and the more-regular role that comes with it, will have to wait.

While Watkins becomes a symbol of hope in Buffalo, Bryant tries to gain the confidence of coaches and quarterbacks, and Archer makes the most of scant-and-scattered reps, Markus Wheaton quietly cements his role as the starter opposite Brown. A broken finger derailed Wheaton's rookie season, but he practiced and played through the injury whenever possible. He has been taking extra throws before and after practice since minicamp, and he has begun to establish the kind of rhythm with Roethlisberger that Brown shares: Big Ben whips the ball to a point on the field, and Wheaton arrives to meet it. "We're building a nice little chemistry, as are a couple of the other receivers out there," Wheaton said.

Wheaton went through what all rookie receivers go through last year. NFL offenses are filled with variations and adjustments that are not seen in most college playbooks. "Last year I was locked on running a specific route, at a specific depth. But there's so much more that goes into it," he said.

"There's so much you have to pay attention to just coming to the line. I've been able to pick that up a lot faster this year, so I am not running to the line with my head spinning."

That head-spinning phenomenon is the reason the Steelers brought in former Saints receiver Lance Moore as a security blanket. It's one of the reason preseason games look so ragged and rookie receivers develop slowly. But it manifests itself in ways that reach beyond dropped passes and errant routes. Confusion slows you down. "There's a lot of thinking that goes into it," Wheaton said. "That can actually slow you down when you are trying to play fast. You can't really play at the speed you want to play out."

The biggest, fastest guys on the track or weight room are not as big and fast as they can be while still learning when to shoot their hands for a pass or recognize the positioning of a defender. That's why counting on a rookie receiver to contribute right away can be so dicey. Size matters. Speed kills. But experience is irreplaceable.