TUCSON, Ariz. -- A few positive days of throwing nearly fooled Rockies left-hander Jeff Francis into believing he didn't need surgery on his throwing shoulder. But the videotape of his only throwing session of Spring Training didn't lie.

Francis, who went from 17 wins in 2007 to a painful 4-10 with a 5.01 ERA last season, said Thursday that he will undergo arthroscopic surgery to determine and fix the exact nature of the injury.

Dr. Thomas J. Noonan, the Rockies' medical director, will perform the operation. While recovery is generally six to 12 months, Francis said it is unrealistic to expect him to throw a pitch this season.

"It's obviously a bad time of year to be making a decision like this, but it's a necessary one," Francis said. "I'm not going to be the pitcher I know I can be [without surgery], and I wasn't last year. And from what I saw on the tape, I wasn't even close."

Francis had a stint on the disabled list in the middle of last season and was shut down before the season ended, in hopes that rest and rehab and cortisone shots would avert the need for surgery. But Francis' agent told ESPN.com on Feb. 4 that he would decide by Thursday, which is the exact day he made the decision.

However, hope arose last week when Francis felt much better each time he threw. Francis even was hoping progress would continue and he could put off the decision.

"I was happy to be in the good weather," Francis said, chuckling. "It had been a drastic change from what it had been."

But on Tuesday, Francis threw a 25-pitch bullpen session, with fastballs, changeups and curveballs, and admitted feeling discouraged at the end of it.

Then he saw the video on Wednesday and noticed that he was making so many concessions in his arm angle just to make pitches, and he could not generate the necessary arm speed.

Francis talked with Rockies manager Clint Hurdle on Wednesday, then slept on the decision.

"For Jeff, personally, I'm happy," Hurdle said Thursday. "I think there's some closure. He got to the place that he pushed it as hard as he could for as long as he could and there wasn't any relief. He has struggled with this mentally and physically throughout the winter."

Francis said the pain is in his biceps tendon, which runs along the length of the arm. Whether that means the problem is caused by fraying in the upper shoulder that's pinching against the tendon is one of the issues that could be determined by the surgery.

This is the third year of Francis' four-year, $13.25 million contract. After a big 2007 season, which included two playoffs wins as he helped the Rockies qualify for their first World Series, Francis was promoted to ace status for the Colorado's staff last season.

However, Francis couldn't locate pitches from the get-go, but said it was during the start of May that he began to notice he was hurting more than normal.

"But it was something I could pitch through, maybe not effectively," Francis said.

Francis could see then that his mechanics were altered, but he thought he could pitch through. But after giving up 11 hits and five runs (four earned) in a road loss to the Tigers on June 28, Francis went to the DL -- with a 5.67 ERA.

Francis returned in August and generally pitched well for seven starts, going 1-3 with a 3.50 ERA. However, he continued to hurt and the Rockies shut him down after a loss to the Dodgers on Sept. 12.

Francis' absence means the Rockies have four of a necessary five members of their rotation in place -- right-handers Aaron Cook, Ubaldo Jimenez and Jason Marquis, and left-hander Jorge De La Rosa.

Francis said the shoulder had "monopolized my thoughts," especially because of the emotional swing he has experienced depending on how the shoulder felt on a given day. But he essentially made the decision on Wednesday, and Thursday morning he was laughing and joking with teammates in the Rockies' clubhouse before announcing the surgery to the media.

"I just want to go out there and be the pitcher I can, and in the state I'm in, it wouldn't be fair to me, wouldn't be fair to the team," Francis said.