You could use that argument yes. Koeman inherited a team on free fall last season and has stabilised us in his first 40 games.
It is simply not true to say it's easier to improve 14 points on 47 than 11 on 62. That is simple mathematics in which it says it's not as big a jump.
We'll have to agree to disagree. Stats can be used to sway whatever you want to believe. Koeman did inherit a team that was in freefall, he also inherited a team that had the talent to push for a Top 4 place previously. He inherited a team that didn't want to play for the previous manager, he inherited a team that couldn't defend. He also inherited the Leagues top scorer. And added some quality in the middle in Gana and Morgan, Given his reputation, I'm a little disappointed in Koeman this season, it seems I'm one of a very few.
But whatever way you dress it up, to improve from 60 to 76 is a better improvement than 47 upto 61/62, and a lot harder to make that leap into the top 4. It's easy to improve on 47 points, from a team that couldn't defend and looked like the players downed tools in the 2nd half of that season, people shouldn't really use last season as a true barometer of the improvement this season as we were so shocking. Even if Koeman hadn't added to that team in the window, I would have expected improvement, new manager, tactics, being able to defend, fresh ideas, getting the most from the players, Leagues top scorer and motivated players.