The 4-2-5 has a lot of flexibility, especially with a 3-3-5 (w/ two off ball LB’s) or 2-4-5 personnel package. The likely base would be a G front with two standup wide 9’s. The DT’s line up in a 2i and a 3, with the 3 to the nickel (to the passing strength). The LB’s line up in a 30.
The two edges have the C gaps, with the DT’s absorbing doubles and playing gap and a half in the middle. The LB’s ball fit behind the DT’s. The safety has time to get to the runner if the front successfully closes off all the interior gaps.
I posted a video in another thread of it working perfectly for the Chargers against the Broncos. All the interior gaps get sealed off, and the runner has to bounce it outside to find three defenders waiting for him.
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