It's not a lazy or nonsensical term when used in the right context, though - what's lazy is calling it lazy right off the bat. Only 'raw' in the terms of a footballer means exactly what it commonly does - crude, not seasoned, and so forth. Someone who is untrained (like a wild horse) and (often) relatively inexperienced, and isn't always consistent with his fundamentals and decision-making. Not to be conflated with sheer talent, because you could very well have a raw player with insignificant amount of talent - which means that you should probably stay off him, in that he'll likely never develop into a top player (eg. Bebé - who had poor fundamentals, was inexperienced and untrained, and didn't really have that much talent to begin with, IMO - though some might disagree). What interests people is that element of 'rawness' combined with a lot of natural talent (particularly athletic - in terms of a natural ability to glide by players, or 'knowing where the goal is', or 'seeing' passes that no-one else does - things that can't always be trained) - hence 'raw talent', which can justify the painstaking process of molding said player over time, with the hope that you can develop him into a great player (like polishing a diamond - a commonly used term).
Essentially, a 'raw talent' evidences flashes of brilliance from time to time because of his natural gifts, but needs to mature (mentally, or physically, or in terms of experience), and be coached up by the manager - making those flashes more consistent and prominent - in terms of improving technique and concentration and conditioning; and trying to have a greater impact on the match instead of a glimpse here and there. And also, sometimes - greater appreciation for team-work - details like that. The raw ingredients are there, but you need the recipe and a flame and a good cook (coach) to prepare the meal.
The perfect example for that would be Hazard at age 16, 17 - when he was starting to emerge. Everyone saw the gifts he had (earning qualitative comparisons to Van Himst and Scifo) - but he was 'raw' in terms of his decision-making and consistency and overall awareness of the game. As he was trained at Lille, he became a sharper decision-maker, more consistent and productive, and had better appreciation for not running into blind alleys, and being mindful of the positioning of his team-mates. Or, someone like Aubameyang - who had it all in terms of physical tools as a forward - but like Hazard, those tools weren't harnessed properly, and he was a 'wild' player - who disappointed despite his rare and explosive talent. A lot of credit for his development goes to Saint Étienne - who channeled his talent in the right direction, after the move to Milan and numerous loans which did next to nothing to develop him. And now he's one of the best attackers around. Or even Cristiano, who was fairly raw at the time he joined United, which is what frustrated a lot of people, in that he would be world class in one game and you saw that 'raw' abiility, and downright awful in the next.
Erm, also:
@Raees and
@Stack have a background of actual coaching. So they will be able to provide a better/ more technical answer.