I don't seem to remember it being as difficult to run down routing enemies pre patch 1.3.

Cavalry seem to pursue them in a tight bunch, like a load of kids chasing a football. The white flag disappears but pops up again about half a mile away. Cavalry all head towards the target, kill it then the process repeats itself. Result: half the enemy escape, ready to inflict more damage on my farms and mills next turn.

Routers scattering is obviously realistic but the inability of the pursuers to do the same is not.
It seems just as bad as MTW2 was before the first patch was released.