When I was the head coach in Winnipeg, I struggled and always lost in arguments with the general manager's insistence to never sign players from other teams. He believed in signing rookies and rookies alone would be the way we would fix any roster issues and or injury problems. That is why we always had the youngest team in the CFL each year. Often times, he would say "why do we want a guy who was not good enough to play for them?" A couple of reasons: one, they understand the rules and systems of the CFL and two, they may be a better fit for our roster than the team that released him.
Some guys may be better than what we have on the roster, which is not what the GM wanted to hear but was sometimes true. What the general manager did not understand is that rookie receivers may be faster on the stopwatch when you are scouting them running down a line. A slower veteran will play faster most times in the game because he knows what to do and what he is doing so those guys can play faster than rookies and the QB's will trust the veterans because they are in the right spot at the right time. Many players are excelling in the league today with very average 40 times.
Another example during my time as head coach in Winnipeg involved signing a rookie International defensive lineman early in the 2012 season over several options that had CFL experience. This player not only had not played in the CFL, he never had played defensive lineman. He was a linebacker who we moved to defensive line. This player did not have a training camp to learn the fundamentals of the position of DL or to learn the rules of the CFL. He was thrown into a very difficult position to be successful, especially early on and also the position coach who had to try to groom a LB on how to play defensive line was also put in a position you normally don't do in professional football; that is teach a player a position he never has played before.
True to form, we had an injury at the defensive line and the player had to start the next week with only four days of practice. He struggled for two or three weeks with lining up offsides, having not had a lot of experience with the yard off the ball. He took three penalties in his first game just lining up offsides. The general manager was frustrated by the penalties and would try to say it was the coach's fault for not explaining that to him or my fault for not teaching him about it. We actually kept track of offsides daily and did extra work when we went offside in practice but these things will happen to young inexperienced players and the best way for them to learn is through game experiences alone. That is how the player will get better at the position, game reps alone.
Ouch. Brutal indictment of the Joe Mack era...