How mistakes can be made in draft

Each franchise in the NFL employs 10-20 college scouts, has extensive video libraries and numerous computer programs, and spends millions of dollars on evaluating college prospects. Nevertheless, mistakes still are made early in the draft.

The ramifications are fairly obvious. You now must find a replacement with quality equivalent to that which you needed from a first- or second-round choice. The waiver wire and free-agent market rarely offer a quick solution. So how is it that mistakes still are made?

Seldom are mistakes made on "measureables" such as height, weight and speed. Almost all first- or second-round selections will possess the physical qualities the NFL team expected. The problems will involve personality, dedication, work ethic, toughness or off-the-field issues.

All of these elements are very subjective, so the picture becomes cloudy. A great 40-yard dash time often will overshadow any concerns about how a player finishes a drill. These characteristics are the most difficult to evaluate, yet end up being the main reason for success or failure.

Assuming you have successfully calculated the measurables and evaluated the person, what else causes the mistakes?

Injuries: This is the most frequent reason a high draft choice doesn't pan out. It is not always a career-ending injury. It can be a succession of season-ending or game-ending injuries.

I signed Kyle Vanden Bosch, a second-round draft choice, three years ago after he suffered several unfortunate injuries in Arizona. When he played, he played well, but the Cardinals struggled to keep him on the field. In Vanden Bosch's first year with the Titans, he was in the Pro Bowl. He has not missed a game and now is the heart and soul of the Titans' defense.

Position changes: Just the fact that a player has the talent to possibly play a different spot does not take into consideration the practice time, experience, coaching, knowledge and instincts needed in the the new role. For instance, Matt Jones is as talented as any player in the NFL, but he was a college quarterback who moved to wide receiver. He still has a chance to become a legitimate NFL wide receiver, but the learning curve has been steep.

If I were to draft a player with the intent of moving him to a different position, I would use only a later-round selection. The idea of using a high pick on someone you will have to teach a new job never thrilled me.

Doesn't fit the scheme: This mistake really should never happen, but it does. Teams will draft a 4-3 defensive end to play in the 3-4. Just because you are a defensive end does not mean you can play that position in all schemes.

A bump-and-run corner will not have all the same attributes as a two-deep run-support corner. If the very best player on the board will not fit your scheme, don't draft him. He won't play anyway.

A need pick: Probably the most common reason for a mistake is when you draft the 40th-best player in the 10th slot because you need someone to fill a hole. Everyone is expecting the 10th pick to have a dramatic impact, and by taking a lesser valued player, you never realize that impact. Not only do you miss on your selection, but now you must play against the 30 players you passed over. If you don't want to draft the 10th-best player, trade down, pick up draft choices and draft the 40th-best player with the 40th selection.

Coach-player personality conflicts: After 15 years of coaching in the NFL, I still am intrigued by how two coaches can look at the same player and see a totally different person. I also am surprised by how one coach can be influenced by another's opinion. I suppose this is human nature, but it also is a reason for mistakes. If a head coach, coordinator or position coach cannot accept a player, for whatever reason, the player's days already are numbered.

The decision-maker must have an understanding of what the coaching staff wants in a player. It probably will be impossible for the coaches to visit every prospect, but it is important for them to have first-hand knowledge of any high choice.

Former Tennessee Titans general manager Floyd Reese frequently contributes to ESPN.com.