By Chris Spielman, ESPN.com

Editor's note: Each week, ESPN.com asks one of its Heisman Watch voters to explain his picks. Here are Chris Spielman's Oct. 23 selections.

1. Matt Ryan, Boston College
Ryan is the major reason for Boston College's success this season. When you take into account the fact that he's putting up career numbers with a new coach, a new offensive system and a number of new receivers, Ryan has shown that he's close to being the best there is in college football.

2. Dennis Dixon, Oregon
Dixon has put up huge numbers in a tough conference -- 1,728 passing yards, 16 TDs; 416 rushing yards, 7 TDs -- and he leads the Pac-10 in passing efficiency. The improvement he's made this year is outstanding, and his ability to both run and throw the ball effectively has Oregon challenging for conference and national titles.

3. Colt Brennan, Hawaii
Not many people are high on Brennan, but I like him. He's certainly done enough to be mentioned in the discussion. He is second only to Texas Tech's Graham Harrell in total offense, and he displayed poise and leadership ability in directing Hawaii to a come-from-behind, overtime win at San Jose State in Week 9. He's a very, very talented football player.

4. Tim Tebow, Florida
Tebow is Florida's offense, and he's proven he can do anything. He's the Gators' bruising, short-yardage back. He can break long runs. He can throw for four touchdowns. Each week, he proves he's among the best players in the country.

5. Mike Hart, Michigan
Hart didn't play in Week 9 because of an ankle injury, but he's still the main reason Michigan is firmly in the Big Ten race after starting the season 0-2 with disappointing losses to Appalachian State and Oregon. Without his determination, ability and love for the game, the Wolverines could still be in the tank.

Although all of these players have established themselves as playmakers, the Heisman race is wide open. Just like the BCS, we could see a whole different top five in a few weeks. That's what makes this so much fun.

Each week, ESPN.com's panel of experts casts its votes for the top Heisman candidates. The panel consists of analysts, former players, former coaches and ESPN.com's college football staff.

A week after Matt Ryan knocked Darren McFadden from the top spot, Tim Tebow has replaced Boston College's signal-caller as the front-runner in the race to New York. The Eagles were off in Week 9, and Tebow used that to his advantage, willing Florida to a win against Kentucky and boosting his Heisman résumé in the process.

Week 9 also saw a whittling of the Heisman field. While Rutgers' Ray Rice and Cal's DeSean Jackson climbed back onto the board, a bevy of candidates did not receive votes from our panel this week. That list includes Texas Tech's Graham Harrell and Michael Crabtree; South Florida's Matt Grothe; Louisville's Brian Brohm; Oklahoma's Sam Bradford; and West Virginia's Patrick White.

The Heisman Watch will be updated each Tuesday. The next update will take place on Oct. 30.

For the complete list of Heisman winners, click here.