So you want to take a very talented goal scoring midfielder and turn him in to a work horse further back on the pitch? Seriously?
If you saw the stat knocking about from Sky last week regarding his goals/assists vs Gerrard, Scholes and Lampard, he's very comparable, favourably so. None of those players played in the role you are advising. Gerrard may have at the end of his career, but for most of it he was played as a number 10 or even out wide. Like Lampard, Scholes and probably now Barkley, he wasn't trusted with the defensive side of the game, or was better utilised where his talents brought the most success, whichever floats your boat.
For a comparison to Zidane's stats at a similar same stage of his career when Zidane was 21 he had played 130 games scored 22 goals and had 14 assists. Zidane wasn't a household name when he signed for Juventus aged 24 but became so alongside Deschamps and some very talented midfielders. Of course it's laughable to compare Zidane who won the World Cup (aged 26) or the one who finished his career at Madrid in his 30's, because he was exceptional. But in terms of attributes it's not the worst comparison to a former player at this stage of his career. Both big strong lads, with similar running styles and goals. I doubt Ross will hit the heights that Zidane did as he doesn't have the same Ghetto drive, or those of gerrard even as he doesn't have OCD, but don't write him off just yet.
Ross scores goals and creates chances. Unfortunately like a lot of the players, his development as a footballer has almost stalled under the Martinez era. Couple that with being ignored in the Euros and then left out of the latest National squad and his confidence is low right now.
Koeman is trying to manage that situation and produce a response from Ross. Hopefully he does so and we see the benefits on the pitch, but people need to give the lad a chance and stop writing him off at every opportunity or groaning and booing if he doesn't meg someone and smash it in the top corner.