This past weekend was supposed to be a celebration for Kory Sheets as his dream of being taken in the NFL Draft came true.

Instead the two-day event turned into a nightmare as after seven rounds and 256 players picked, the former Boilermaker running back was on the outside looking in.

The fact that he went undrafted surprised many as most of the mock drafts had him going in the third or fourth round. No one was as surprised at what transpired more than Sheets himself. Simply put; Sheets was shell-shocked at the developments.

"I went from having a smile on my face to having a blank look on my face," Sheets said.

"It was very disappointing, shocked and heartbroken. It broke me down to my lowest point that I've been in a long time. I couldn't believe what was happening or why it was happening."

Sheets admitted by the middle of the sixth round he felt he wouldn't get drafted.

"I got up and said, 'I'm not even going to watch this, because the more I watch this, the harder it's going to be to keep composed,'" Sheets recalled. "I just went downstairs in my room and laid down and waited for somebody to call me."

Sheets believes he knows exactly why he wasn't drafted by none of the 32 NFL teams.

"I was told what happened," he claimed. "My agent had talked to several GMs and coaches and they were saying basically that the (former) coaches at Purdue were saying I had character issues and a bad attitude and they didn't want to risk it … paying me the money and me coming in and having a bad attitude."

When asked where the bad attitude label stems from, Sheets said, "just my demeanor around Purdue in the football facilities. I wasn't the happiest person and everyone saw that. I could've done a better job hiding it. I'm just the kind of guy who wears his emotions on his sleeve. I'm going to be up front and honest with you. I guess that was too much for the coaching staff to handle and they didn't like it."

If you couldn't tell, Sheets thinks he's gotten a bad rap to say the least.

"I think it's real unfair because at the end when it came to football I always gave my all and was never a guy who slacked," he said. "I played to the best of my ability every time I was on the field and had the ball in my hands."

Even with the character issue cloud hovering over his head, it's not like some of the players taken in the draft didn't have some baggage.

"One guy got in trouble a bunch of times and he got drafted, and I was kind of shocked when I saw that," Sheets said. "There has to be something more than character.

"I'm not a bad person."

Sheets pointed out that he was never arrested at Purdue, never flunked a drug test and never was suspended from the team.

"I would really love to know why I wasn't drafted," said Sheets, who graduated from Purdue in December.

"If you read all those (mock) drafts, they say I have all these plusses and the one minus is a character thing.

"But people have had character issues and have gotten drafted so I guess whatever was told to the GMs, it was so bad that they didn't want to risk taking me," he added.

Earlier this year, Sheets was confronted with the character issue concerns by NFL brass when he was at the Senior Bowl.

Some of their concerns centered on what he said following the 2008 loss at Northwestern.

"I got a lot of questions about the whole situation at Northwestern saying what I did and people believing it was about (Curtis) Painter, but it had nothing to do with Painter," Sheets admitted.

"Painter is a player just like I am. He does exactly what he's told. All he was doing was what he was supposed to do. It had nothing to do with Painter, but it got blown up and twisted like I was talking bad about my quarterback when really I was just upset and just wanted to win games and it seemed to me like our (coaching) staff wasn't doing much to change our situation or put us in better situations so we would have a better chance to win. That's all I was really saying and people took it and twisted it to make it say like I was saying Painter was the reason we were losing and if he was on the field we weren't going to win, which was not the case."

Don't think Sheets is going to clear his mind of what has happened. He's going to do just the opposite.

"I'm not going to put this behind me," he said. "I'm going to use it and keep it in the forefront of my mind and make sure nothing like this ever happens again because at one point I was thinking that I might never get to play football again and would have to get a regular job.

"I'm going to use it as motivation. It's a bad thing that happened, but I'm going to turn it into a positive."

There was a sliver of positive news Sunday for Sheets. A few teams were interested enough in Sheets that they extended free agent offers to him. Towards the end of the sixth round, teams like San Francisco, Green Bay, Denver and the New York Jets and Giants began to express interest in him.

Sheets and his agent decided Mike Singletary's 49ers would be the best place for him.

"What my agent was told and what was told to me was that would be the best place for me to make a team," Sheets said.

Sheets realizes his chances to make a roster aren't nearly as good as they would've been had he been drafted. He also knows that there's a big difference in money between draftees and free agents.

"I'm guaranteed some money, but it's no where near the money I was told I would've received had I been drafted say in the third or fourth round," Sheets said.

Sheets' believes not being drafted cost him hundreds of thousands of dollars.

So Sheets will go out to the Bay Area and try to impress enough to do the improbable - make the 49ers' roster as a free agent.

"Once I get out there, I'm going to forget that I wasn't drafted and think I'm on the same plane as everyone else," said Sheets, who left his home state of Connecticut for the 49ers' rookie mini-camp Thursday. "I may have to work a lot harder than everybody else, but that's fine. I'm accustomed to working harder than everybody else because at Purdue had had to scratch and claw for every little bit I got."

Most importantly Sheets plans to show his coaches, teammates and everyone associated with the 49ers' organization that he's a good character guy, too.

"What's basically been said about me is exactly opposite of the person I am," Sheets said, "and anybody who has played with me can tell you that."