Babel never had the luxury of continuity of games like Downing or faith from the manager. You feel like he was just in a constant mode of frustration having to compete with up to 4 players per season for that 1 left wing spot, rarely used elsewhere where he could've been useful like the right wing or back up striker. He is one of those emotional players. I feel his crossing ability was underrated, so playing RW where he could just knock it past his man would work better than trying to cut inside and dribble from the left.
Babel to me didn't really seem that intelligent for the most part, but as Discipline said, there was definitely an ability to fit in with intelligent players and play to their level - this really became apparent when we indeed started playing true pass and move football with Aquilani and Gerrard in the side. He came from Ajax after all. He had some ability/intelligence to get in position for those tap ins too like Benayoun/Kuyt but not as often. He had potential but we didn't unlock it and his career has gone to shit.
His stats would've been much more productive had he started more often. He is one of those players that somewhat neglects defensive duties in order to save energy for attack e.g. in the Neymar, Hazard role but Benitez didn't like this even though he had Kuyt to balance on the other side. Babel FINALLY started working hard in defence towards at the end of Benitez's reign and was rewarded with more time, but it was too late - Roy came in and gave him even less opportunity and then he was sold before Kenny could use/help him.
All of this said Downing is a different player, and though I'm disappointed for the most part, I still believe Downing can improve heavily and increase his output almost 10 fold next season. Has been unlucky many times, a few mediocre performances in between but he has the tools, he can definitely play a good link up game but he is a part of it not the instigator, we just need a catalyst for pass and move football in the centre (like and Aquilani type). We need him to fire at a decent level next season even if we bring in a new wide man, there is no way he will end up with 0 goals in the league and less than a handful of assists.