When the offense is spreading teams out and trying to use the quarterback read to gain a numbers advantage, they tilt the numbers advantage to their side.
Offenses around the country have started using the zone read game to have the quarterback attack the backside of the inside zone.
On the zone read the linebacker can get easily sucked into defending the threat of the inside zone from the running back and can lose his ability to make a play on the quarterback if he keeps it.
A simple fix that defenses across the country have been going to is to get the safety involved in the run fit. The effect of using the safety to come up and stop the run is twofold.