Grenades., Throwing an idea out there, seeing what people think. Options

[FuelDrop]

Now to the best of my knowledge Grenades are pretty deadly in 5th edition. One of the main factors in this is that there is no way to effectively avoid their very high damage.

I am here to suggest a possible houserule, an interrupt action specifically:

Fire in the hole! (-5 initiative score)
A character may choose to take evasive action in an effort to avoid a grenade or missile blast. This can mean diving behind cover, fleeing as quickly as possible or even dropping to the ground and praying. If the character is within cover they may make a reaction + intuition check with a bonus based on the cover they are behind (commonly +2 for soft cover and +4 for hard cover). Successes from this check reduce the grenade's damage before soak is rolled. A target out in the open may choose to either flee or hit the dirt. If they choose to flee they may make a running or gymnastics check. They manage to run 1 meter from the point of detonation per net hit, though at the GM's discretion obstacles or walls may limit success. The character flees directly away from the explosion, which may potentially place them in other danger. If they choose to hit the dirt they become prone but damage from the explosive is reduced by an additional 1 point per meter from the point of impact on top of the normal damage drop-off, or gives a damage dropoff of -1/m to weapons that do not normally have such a dropoff (EG flash bangs).
The 'Fire in the hole' action has no affect on the effect of gas or smoke grenades, and only a single such response can be take per action phase.

Okay, I am violating the first rule of rule design here (Specifically, K.I.S.S.) but it was either that or create three separate rules.
Can anyone suggest how I can modify this to avoid players dropping grenades at their own feet to use the flee action to increase their speed?