I heard Nolan Ryan also speak of using a football to get loose before games. If the throwing of a football messed up throwing a baseball, there is no way Nolan Ryan would have done it.
I also read a book by Nolan Ryan called Kings of the Hill where he tells how he was introduced to using a football to help his pitching.
I believe it was something that Tom Morgan suggested to him in 1992. Ryan was very skeptical at first, but tried it, and it worked. He had over 20 years in the game, yet was not against trying something new.
Furthermore, to quote Ryan from his book, "So now I throw a football between starts more than I throw a baseball." Tom's theory is that you can't throw a spiral unless you have the proper mechanics. "...so even on the nights I start, I throw the football for about 5 minutes before I take my regular warm-ups."
As a coach, I always have a football in my team bag. The boys have fun with it before practice as kids arrive to the field. I also use it for the youth outfielders as part of organized practice. At this age, any good arms are in the infield, so having my outfielders throw the football really helps them get the weirdness out of their throwing motion. They just think we're having fun with a football. One critical thing is to be sure it's the proper sized ball for the kids you are coaching.
I highly recommend it to be in everyone's team bag!