re: The missed tackles will be a thing of the past .

Missed tackles are a symptom of modern football.

First - they have limited contact hours compared to years past, particularly during the season.

Second - most modern coaches monitor closely the number/duration of live tackling sessions, again - particularly during the season.

So, the focus is on scheme, preparation and execution - pre-snap reads, post-snap adjustments (on defense), which necessarily cuts into the already finite practice time. And, finally, the scout team offense does the lion's share of "getting tackled" and they're not as fast or elusive as the 1s and 2s on offense.