I went through the play-by-plays posted at ESPN.com to find the Rams longest drives (in terms of time) this season. They are posted below. If one were to check some of the Rams previous seasons over the last decade, when they specialized in the three-and-out, I'm sure the disparity would be dramatic and perhaps the best indicator of how this team has been transformed by Sean McVay.
7:22 Redskins
5:43 49ers
5:16 Cowboys
5:06 Seahawks
5:08 Jags
5:50, 6:53, and 10:19 Cardinals
6:40 Giants
6:26 Texans
5:28 and 5:28 Saints