Well, partially you are right, an injury time-out is a factor, but given Donna's age and inexperience on the big stage (compared to Hlavackova, who has won huge titles and an Olympic medal in doubles), Donna could've easily choked this match away, like so many of her peers would in the same situation. An in-form Hlavackova surely would've been a bigger obstacle, but if we consider the scoreline, I'm not sure Donna would lose it. We can also say that Donna had quite a long break, of course minus the injury, cause she played her last competitive match in early November.
And could you please define "big results"? For me, for example, a big result is a 4th round of a grand slam, because of how rarely our players ever got that far. I don't think we'll have to wait 4 more years to see Donna achieve it. Also, winning any WTA title is a big result if you ask me (Majoli has done it only 8 times in her whole career), and Donna was already a match away from achieving it.
I think we Croats as fans suffer from too high expectations syndrome
, and need to try to play the sport ourselves in order to appreciate results of our pros a bit more. But then, with grand slam champions and Davis Cup winners, who wouldn't be spoiled...