Morris should really flourish behind this OL, and he can definitely pick up a blitz on passing downs.
If given the opportunity and he stays healthy (durability hasn't been an issue for him) he'll be more productive as a "runner" than McFadden was last season. He's shifty, has great vision and is decisive. Some of his best runs have been weaving his through traffic he seems to find a way to break free. Another thing I like about him is he can put TD's on the board. In 2014 he had 15 fewer yards than McFadden did last season but put up 5 more rushing TD's. He's produced 29 rushing TD's the past 4 years compared to only 12 rushing TD's for McFadden. Can't understand why some aren't very enthused about picking Morris up I think he'll end up being the best free agent pickup we've had in awhile if he can improve as a receiver. He could be very productive running the ball behind our OL and as a redzone/goal line threat.
A part of the reason why his numbers have declined is because his carries have gone down each year and Washington had implemented a Baylor-like offense for RGIII in 2012 and tried to transition from that the following season. When that didn't work Shanahan got fired and the entire offense was reworked under Gruden. When Matt Jones was drafted Morris was relegated to splitting carries with him. He could really flourish in a return to the zone blocking scheme. I will say this that Morris did benefit a lot from the duel threat RG3 brought to Washington in 2012. Morris was better with RG3 on the field because without him at all in 2015 he averaged under 4.0 a carry for the only time in his 4 seasons.
Once concern I have with Morris getting the opportunities he needs to be successful is he hasn't been much of a receiving threat which is a staple of Lineman's offense. The way the Cowboys used their backs last season as receivers makes you wonder how they will use Morris. As a "runner" he can be very good it's going to come down to whether he can pick it up as a receiver because that's a big part of the Cowboys offensive game plan.