Good addition, but limited usage - just for top-ups... simple math

18 player squad (average size)
6 packs for 5% for each of those players .. of course only 11 play and 14 if you count for 3 subs
If you use targeted boosts - 14 packs would get you 15% for each of those 14 players
whereas with Rest ALL option - would be 18 packs

Break-even if you have a squad size of 14/15 (thats what is the design baseline I presume), as you have more players in your squad the option becomes progressively expensive