As I think was hinted at above, the 10 minute games we play represent the match highlights. If we forced more walking play into the game, I think it would make it too boring.
If the game is merely slowed using the current game speed adjusters, it doesn't affect anything except the thinking time we have.
I can see two ways to reduce the amount of sprinting in the game :-
1) Apply cool-downs for the players, where they can only sprint for a given amount of time in one go, with a sprint bar rising to full. And once you stop sprinting, the bar slowly reduces, meaning you can sprint again before it drops completely but only for a shorter time than usual. The player stamina rating and usual in-game fatigue can affect how long this bar can be and how slowly your player recovers.
2) Reduce the overall stamina of players in the game, making us have to properly regulate how often we set a player to sprint. However, I can guarantee that you will get people complaining that their players get tired too quickly. I know this, because people already make this complaint. LOL
I do point 2 above already, to try and keep some players fresh for the last few minutes.
How do you apply cooldowns? Is there an option in game? If there isn't...might be hard to pull off, since the CPU AI will not abide by those same rules, you'll be forced to sprint or pass if they charge you which they do very frequently, regardless. If there's an in game option that would be nice!
Secondly, I see both sides to your #2 idea....players do get tired too quickly, but they don't get exhausted fast enough.
In game it's more of a gradual consistent decline from 100% stamina, with the decline from 100% to 80%, being at the same speed as 20% to 0%. I wish it was more like real life. Where players operate at full or at least near optimal capacity for a long sustained period of time, until they do start to tire, but once they do start to tire, their energy, and performance start to degrade very rapidly.
Think about how the body naturally works. I mean athlete's are probably not even at their optimum, until 10-15 minutes after they start working their bodies. They are probably faster, looser, stronger, more focused, once their biological systems kick into full gear, it probably takes that long for the Anaerobic system to start kicking in after the Aerobic.
And then you're good for a while until you start to tire, but when you start to tire, things go downhill fast, exponentially faster. Think of an average person bench pressing their body weight 10 times, they probably get the first 7 up fine, their muscles start to feel tired around 8 but they lift it up fine, number 9 comes up very slowly, shakily...and 10 ends up being a failed attempt, or assistance needed.