Some would say that's where the "trapping" comes in. Conceptually this is correct. If they're covering up on the blast (hands come up to shield) you would have to "remove the obstruction", thus "trapping".
However that works in theory and doesn't usually play out in practice as nice and tidy as it does when people teach it in training. That’s because people resist more in fighting application than they do when you’re in “learning mode”. You have to take it “live” and go against someone really sparring you back.
One thing I've noticed is the straight blast while fast, doesn't really generate a lot of power. This is why many are using the boxing blast now. Either way, when you blast and come in on your opponent, you will be in the clinch. Thus it’s important to have a good clinch game, because that's where you'll be fighting from that point on. This is particularly true when you are using it against a worthy opponent.
Again, the best use of the straight blast is as a offensive, defense. Use it as cover-fire as you’re closing the distance to get INTO the clinch (unless you are using it to create an avenue for escape). Thus you will be entering the clinch as an objective and not just having it “happen” coincidentally.
One strategy is to blast into the clinch and look for the muay Thai plumm position or an underhook and collar tie (“pinch”). Once there begin throwing knees. For self-defense, grab their hair (if they have any) and use the grip as you would a plumm. Throw knees to the face or groin and not the mid-section.
If they’re wearing a jacket (or even a shirt if you can grab it), grab the material behind the neck and use THAT for control (hockey style). Pull the material up over his head as you have him bent forward. Throw knees. Pull him straight down or twist him to the pavement and hit a knee-ride or run away.