[MLS] A lot of youngsters have earned regular playing time this season but the field is a bit short on truly outstanding prospects.

It’s not unusual for rookie defenders to make their mark in MLS, and take home the Rookie of the Year award.

Last year, Omar Gonzalez was a runaway winner, and in the past decade Sean Franklin, Jonathan Bornstein and Michael Parkhurst have taken home the prize. But attackers aren’t out of the running, as shown from 2001 to 2004, when the prize went to, respectively, Rodrigo Faria, Kyle Martino, Damani Ralph and Clint Dempsey.

Nor can a solid two-way player be ignored, and thus did Maurice Edu (2007) strike a chord for the guys who can go both ways. And truth be told, left back Bornstein played some midfield in 2006.

As for the rookie class of 2010, it’s very much a smattering of different sorts. Philly forward Danny Mwanga is quickly developing into a fast, powerful goalscorer that first-year defenders like Ike Opara (San Jose) and Tim Ream (New York), as well as most of the others, are stretched to contain. Galaxy midfielder Michael Stephens has stamped himself a regular member of a very good team, and spectacular 17-year-old Andy Najar is seemingly destined for great things even though D.C. United is apparently not.

Ralph set a high rookie standard in 2003 when he scored 12 goals. This season, Mwanga, with five, is tied for the lead among rookies with Zack Schilawski of New England, and has exceeded the goal total (four) compiled by finalist Kheli Dube in 2008.

In 2005, Scott Sealy hit nine goals and Chris Rolfe scored eight, yet both lost out in the voting to the Revs’ sensational defender Michael Parkhurst. As the overall No. 1 pick, Mwanga has been closely watched. With Philly yet to play one-half of its games, he will have opportunities.

Stephens is a very different player than 2007 winner Edu, yet he stepped right into the Galaxy midfield. He can link the back line to the attack, as his seven assists illustrate, and is still learning the positioning and timing essential in midfield. His possession game has fluctuated but on the few occasions he gets off to a bad start, as he did last Thursday in a 2-2 tie with San Jose, he usually gets back on track quickly. (He could become the first Rookie of the Year taken with a team’s only pick in the applicable SuperDraft, and would also give the Galaxy three straight winners.)

Ream enjoyed a great first month, then contributed to a few bad goals with errors and indecision. He got some valuable experience last week in the Barclays New York Challenge. Since he lacks the physical tools of 2009 winner Omar Gonzalez, he relies on quickness, confidence, and a very efficient presence with the ball.

No longer does Opara need to shuttle between the Quakes and classes at Wake Forest. Fast, strong, likeable, coachable and with a nose for goal (three scored plus more caused by getting to the ball), San Jose is well set with him at center back. Far less heralded but also getting good minutes is teammate Steve Beitashour, who has played both right back and right mid.

Attackers Tony Tchani (New York) and Teal Bunbury (Kansas City) are promising prospects. Zach Loyd is helping out in Dallas. Blair Gavin is a regular for Chivas USA. Seth Sinovic is on the field a lot for the Revs, and Steve Kinney (Chicago) hit the goalpost twice with headers on his debut, then scored in the next game.

With three months of the regular season still to play, here’s my top five Rookie of the Year candidates:

1. Danny Mwanga (Philadelphia)
2. Michael Stephens (Los Angeles)
3. Ike Opara (San Jose)
4. Tim Ream (New York)
5. Andy Najar (D.C. United)