I think numbers are the easiest way to differentiate 2 characters to the user, whether in a sports game or otherwise. The difference with sports games is that the user has to constantly make personnel decisions deciding between one player and another. For a casual gamer the current system is nearly as easy as it could possibly be and it is about as easy for the programmers as it could possibly be.
That said, it isn't the most realistic system. There are three other options that I like, any of which I would prefer to the current system. Within any of these systems though you still need to have basically the same ratings system running the gameplay behind the scenes. All we are really discussing here is a different way to show those ratings to the user.
Probably the toughest one both for the programmer and for the end user but one that could be kinda interesting would be written reports something like the scouting reports in the original head coach, From a programming standpoint this presents some problems having enough text so things don't get repetitive or to easy to scan for keywords and know the exact results but it is obviously possible because to some extent it has already been done. For the user though this requires a lot of reading which would be a problem. If they were to do this I think I would prefer it going along with another one of the systems.
The next option is an ability style system like APF used. Here, based on a players ratings a few icons or abilities or some representation of their strengths and weaknesses are displayed rather than actually displaying the numbers. This system has its strengths and weaknesses. The biggest strength is that it is a more realistic way of presenting the info to the user and it leaves some of the ambiguity that makes real football personell decisions more interesting that those in the current system. The main weakness is how the CPU interacts with this system. Either it interacts with the numbers in the same way as it currently does which puts the user at an extreme disadvantage because the cpu would still alway be right and the user would be guessing, or you have the cpu interact with the icons or abilities like the user would putting the CPU at a huge disadvantage because it doesn't have all the knowledge of players the the user might have and if we get actual draft presentation it wouldn't have the same way to know things about the incoming players that the user would. This would lead to a need for way more house rules than their already are. Also, this system leaves very little in the way to show any progression to the user which would lead to a whole new set of complaints.
The third system, and in my opinion the best, would be the one I described in the thread about eliminating the overall rating. Basically it takes the positional philosophy system from HC 09 and the range system from the original HC and combines them with a few anvancements. I am not going to write it out here as it is a pretty long explanation with a lot of details.
The advantages of this system is there is still a real way to differentiate between the players while still leaving a good deal of ambiguity to most decisions. It also leads into a lot of interesting possibilities with scouting and also with making the preseason actually matter and also with the ranges adds in some inconsistancy to the players opening up possibilities for cold streaks, hot streaks, players playing at the lower end of their range getting benched and cut leading to gems in free agency or trades or playin at the top of their range leading to busts in free agency or trades. Also, it brings in the production grade from HC which allows players who put up big numbers to retain starting spots and get realistically larger contracts without falsely increasing their ratings. With the philosophies it allows differentiation between what different teams want at different positions as well. Also, this being a number based system makes it easier to put the CPU on an equal level with the user.