PORT ST. LUCIE, Fla. -- The guy at the other end of the throw smiled whether or not he caught the throw. If the baseball rested in his mitt, he beamed with pride, having offset the unnatural forces that had worked against him. If it bounced away, he smiled because it hadn't struck him in a unprotected area and laughed at the absolute absurdity of of the experience, the implausibility of the path the ball had followed. Yes, knuckleballs often are funny.

They move like a bee being chased by a bird. No rotation, no predictability, no chance of catching one and no one who wants to try. Hitting one is a greater challenge, but not one has tried that here yet.

The Mets do have a knuckleball in camp. It belongs to R.A. Dickey, a 35-year-old refugee of the American League invited to camp as a non-roster player and, unintentionally, as a sideshow. Everyone stops to watch his pitches. And they smile, too.

Dickey once threw conventional pitches at high velocities. Guys at the other end of those seldom smiled then. But when the back of his right shoulder balked and his velocity diminished in 2005, he enlisted the help of the pitch that makes hitters and catchers alike quite antsy.

Dickey was throwing in camp Sunday, just loosening up his right arm in the outfield. Dave Racaniello, the Mets' bullpen coach, was the guy on the other end, 60 feet away. He was laughing and, on almost every throw, adjusting his feet to avoid injury and embarrassment. Racaniello has been with the Mets since 2000, the last year a New York pitcher -- it was Dennis Springer -- threw knuckleballs in a big league game. And he was with the team when Charlie Hough, a recognized past master of the pitch, served as the pitching coach. He has caught Hough (but only at 50 mph) and Springer and now Dickey.

"It doesn't get any easier if you do it a lot," Racaniello said.

Dickey hopes that's the case for the hitters across the Grapefruit League between now and the first days of April. Perhaps that pitch can deceive enough of them to make Jerry Manuel, Dan Warthen, et al consider adding a knuckleball to the staff arsenal. It certainly would afford the staff an alternate look. But chances are there will be no room for Dickey on the 25-man roster that begins the Mets' 2010 season. Then again, no room existed for Springer in 2000, and he started two April games for the team that played in the World Series.

Self-described as "a little bit of an eccentric," Dickey is one of the three "outside-the-box" pitchers in Mets camp. Pedro Feliciano, now regarded as part of the furniture after seven seasons in Flushing, does throw from 3 o'clock, which makes him unpopular with Ryan Howard, Chase Utley and their left-handed-hitting brethren. And now Sean Green has dropped his arm angle to almost 8 o'clock, imparting greater vertical movement to his pitches.

Feliciano is all but guaranteed a place on the roster. Some folks around the Mets last season considered him the team's most valuable asset; if not that, then he was at least the player who did his job best from April to October. He has continued development of his cutter to make right-handed hitters more uncomfortable.

Green, after an uneven 2009 season, is not as secure, but he certainly could emerge as a mid-to-late bullpen guy. He isn't scraping his knuckles on the mound's third-base side slope a la Chad Bradford, but his altered delivery does make him appear less vulnerable to left-handed hitters. In discussing Green on Sunday, Manuel suggested the righty could serve as a cross-over reliever -- one who can prosper against right-handed and left-handed hitting. The manager has longed to find one since he replaced Willie Randolph in 2008.

But neither Feliciano nor Green, nor any of the other potential members of the bullpen, throws a pitch remotely akin to Dickey's knuckler. "I used to play catch with him a lot with the Mariners [in 2008]," Green said. "Some guys who throw it will let up on you when you're just throwing, getting loose. But he's relentless. ... My hands aren't great, but I'm OK. And his stuff just exposed my weaknesses."

Catchers aren't Dickey's best friends, though Omir Santos -- out of a job once Rod Barajas passes his physical Monday or Tuesday -- seemed to have no problem with Dickey's pitches Sunday. And Barajas, for that matter, was a competent knuckleball receiver when he and Dickey were Rangers teammates from 2004-06.

Dickey threw his knuckleball -- he calls it "a working man's pitch" -- occasionally even before he injured the back of his shoulder. "Maybe four or five if I threw 100 pitches in a start," he says. After Dickey's velocity diminished, Rangers pitching coach Orel Hershiser and bullpen coach Mark Connor urged him to use the knuckleball more. That suggestion brought him opportunities with the Mariners, Twins and now the Mets.

"When he has a good one working, it's as good as any in the game," pitching coach Warthen said. "He's had good teachers -- Hough, Phil Niekro, Tim Wakefield -- and he knows his trade."

All of which is to say, Dickey is equipped, but not as consistent as he might be with his pitch.

Because of that and because the Mets have all sorts of candidates for the few pitching assignments that appear to be vacant, Dickey can't begin to figure out what this camp will bring. He doesn't know where it's going, like one of his pitches.