You should always be flexible and be able to adjust to the opponent. The reason “base” gets thrown around a lot is because most teams generally play with 11 personnel and most teams use a no huddle offense at least part time. You have to play some type of nickel against 11 personnel and if the opponent isn’t huddling, you can’t sub guys in and out. The general catch all defenses for those situations usually incorporate an extra DB but like you said, if the opponent in running 12 or 21 personnel, you have to alter your defensive personnel because the nickel guy (whatever you want to call him “striker”, “star” “rover”) is going to get manhandled by a blocking tight end in a power scheme.
I know “multiple” gets thrown around a lot and a lot of people don’t really understand what it means but it’s pretty much mandatory in today’s game. You have to have guys with positional versatility and you have to have as many different looks on defense as possible without having to make wholesale substitutions to do it.
You're correct regarding substitution, but the difference between a strong safety, nickel, or Sam backer player are so minimal and are more or less based on measureables.
What I was referring to adjustments like Manny vs MSU... There weren't any, he played his "striker" out there, sniffing the box at 6 yards off, when when they have TE, FB and a TB. As soon as I saw that I knew we were gonna lose and get ran all over.
Regardless of personnelle, your alignment should be proper, for aiming points and leverage, those players still have to block or tackle. That what I care about and that's what matters more, pre snap alignment is the number one thing for defense. I know myself and
@Coach Macho were pulling out our hair with Manny defense cause it was fundamentally unsound as a base because of the previously mentioned.
I'll use Lashlee as an example, when he ran trips to the weakside of the field, a DC has a really tough time dealing with that formation, cause it's 100 percent pick your poison and why it works, look into yourself and figure out the weakness as a DC against that, you'll figure it out. Used that myself as an OC.
Manny was terrible for this, not entirely sure he knew what he was doing and relied simply on making a mess, do whatever you want and have the back end clean it up, which is a nightmare.