I think he's talking about Ostheer Mechanised Assault doctrine.
First rule of Mechanised Assault is to know what the doctrine provides that you can rely on without tech. Going only for Assault Grenadiers is a poor choice, so it's always worth building tier 1 for three Grens, possibly a mortar if need be. Assgrens are a unit that will complement a strategy, not dominate it, so if you're on a very urban map they can help, but don't expect them to do too well if you try spamming them.
Usually, Mechanised Assault players will go for tier 1 for baseline infantry, then tier 2 for paks and other light vehicles, and complement it with the pgren halftrack if needed or wait for Stug Es.
With the Tiger being 13cps, you'll struggle to just sit out and wait for it with your Stug Es. I'd always recommend building your tier three tech for more robust Stug Gs and the occasional P4. The Tiger call in will be expected, so don't be surprised if an enemy is prepared to deal with it. Your strategy will vary depending on what map you choose, and it's entirely possible that you decide going all the way to tier 4 for a panzerwerfer is better, or get one after your tiger.
But I must stress, don't skip tier one, because Mechanised Assault is very weak if you rely only on the call ins.
I am talking about that commander indeed.
I only pick this commander against USF.
What I usually do is to get 2 assault grens and 2 mgs then tech t2. Get early pak and mechanized assault group during t2. Then get t3 and a panzer IV, and finally call in a tiger.
For late game I usually end up with 2 assault grens, 3 panzer grens, 1 or 2 mgs, 1 pak, 1 panzer IV and 1 tiger.
Kinda late indirect fire potential.
Btw, this is for 1v1