Nothing much to say about this one, as you said this was his first match of the season after bad knee injury and we all have seen how some other great players had problems to return. Zverev needed a lot of time after breaking an ankle and Thiem never properly retuned and both are way younger than Čilić.
yeah, Thiem never properly continued playing tennis after injury
I am always having DelPo on my mind when hearing about injuries, pretty sure he would have 5+ GS's if not for so many injuries, even with all three top players playing at same time
off-topic, Djokovic is on vacation in Dubrovnik, as I can see, but not giving interviewes regarding Wimbledon
Still remember how Delpo had to start playing backhand slice instead of his booming hits just to have a chance to play.