[jaredhallen]

The malt definitely had less diastatic power, which is its ability to convert the starches to sugars during mash. They may have had some tricks of the trade, or they may have just ended up with less conversion. If it was the latter, you could manipulate your mash to emulate, but without knowing the goal you'd just be guessing. And the yeast, you're absolutely correct. And that's one of the biggest contributing factors in the finished product, especially with no hops involved.