I would still like to see him do atleast one whole game at LB, as this was not ideal situation to test him, with so many goals upfront and against 10 players.
If Alba is unavailable for next game, definetly give him a chance
im concerned that using roberto in different positions make him not to focus or get improved as well as normally should be in a particular position.
or at least use him only as CM/AM , or just DM , or LB/RB.
the gap ( in many aspects ) between a midfielder or a defender is too much.
I think in Roberto's case playing RB/LB spots helps Improve his overall game in Areas that help him in the mid.
-Defense
-Attacking
-Positioning
-On/off the ball Skills
-Confidence
I think Roberto sees these chances at the FB Positions as more playing time obviously and good training like I said above. Before Lucho forged him into the player he currently is now, He was always pretty great at reading the game and good at his Positioning in the Midfield.
But what he lacked was his Confidence in his final Ball. It looked like he was afraid to make a gutsy through ball or a Forward pass as you can say and he preferred to keep it safe. When Lucho played him at RB it really upped his Confidence and improved several aspects of his game and it helped him Improve gracefully in the CM role.
Things started looking up for him actually when Lucho played him as a DM for several games last season it got even better when Lucho used him as a RB in Preseason and onward.