I agree with Bunzo , way too late in the season to buy players - you have maybe 4 or 5 games left if your in the CL/SL final so its a bit of a waste of time/money/ resources.
However your player de Costa would never get into my teams as he is. Far too slow for an outside defender ( remember he will be up against AML/R type players and most of them are trained to be fast. Speed kills in my mind and I wont have a player under 80 - 100 speed in my team in any position to start with , then I will train them to be faster. Also I find fitness relatively important for recovery from games which is important when you have 2-3 matches in a day.
I will sacrifice a little bit of attack/defence skills for superior physical/mental attributes early in development and then later once the P/M skills are to a decent standard I will extend the A/D attributes some more. It is a balancing act to be sure. I know some will say dont waste time and effort on gray skills , only train white , but what I am finding is that well rounded players are at least the equal to the few mutants I have seen and in most cases ( unless the mutant is high in fitness) will finish the game off more strongly than the mutant so the last 30 mins of a game are usually mine to control against tired opponents.