Playbooks

Duo out of Maryland I Tight Close is a downhill gap run play designed to attack a single hole with double team blocks at the point of attack, freeing a lead blocker to climb to the second level. The offensive line combo blocks the defensive line to control the interior gaps while the fullback leads through the hole to pick off the first linebacker that shows, and the HB reads the double team before making one cut upfield. This is a power run concept, not a man or zone beater in the passing sense, and the primary read progression starts with the double team blocks on the front side before working to the fullback's kickout or lead block on the linebacker level.
Watch for stacked fronts with extra defenders in the box, a heavy box (seven or more) can overwhelm the double team before the fullback gets to the second level. Key the middle linebacker's depth pre-snap, if he is sitting shallow he can beat the fullback to the point of attack and blow up the play. Post-snap, identify any user-controlled defender flowing hard downhill, that lurking defender can shoot the gap before the double team locks on. Look for slanting defensive linemen, a hard slant into the play side gap can beat the double team combo and force a negative play. Man coverage on the backside with no extra run support usually means this play has room to break, but zone shells with linebackers sitting in run fits force the back to bounce or cut back late.
Run this out of 30 personnel when you need to establish clock control and wear down a light defensive front.
Check the box count before the snap, Duo hits best against six or fewer defenders in the box since the double teams need numbers to work.
Use the fullback's block as your primary post-snap key, if he climbs clean to the second level, trust the hole and hit it downhill rather than bouncing outside.
Pair Duo with Power O and FB Dive from this same set to keep defenders honest on gap direction, then mix in PA Boot or PA Power O once the defense starts crashing hard on early down runs.
Best called on early downs (first and ten, second and short) to stay ahead of the chains and set up play-action shots later in the series.