Having watched a fair chunk of the match, I guess I can jump in on why he lost.
In hindsight, he lost the match in the 2nd set when he had several chances to get the vital break and grab a 2 sets lead. I don't think there is any way Karlovic would've had the mental strength to come back from such a deficit.
The defining point was when Karlovic was serving at 4-5 in the 2nd and Hewitt lifted his game and played some inspiring passing shots, leading to a set point opportunity. Karlovic had served several double points on previous break points and was clearly nervous. After serving a fault, he served a very short second serve that bounced up and (with Karlovic at the net), all Hewitt had to do was get it past Karlovic and the set and match was his.
But he mi**** it, and never looked like breaking his opponent's serve for the rest of the match. The window of opportunity was lost.
Hewitt was rather unadventourous throughout, not going to the net often enough and relying on beating his opponent from the back of the court. He should've been forcing the play by going to the net more and making his opponent hit winners, instead he let Karlovic settle in the 2nd set and he never looked back.
Karlovic is no mug mind you. He's one of the few genuine grass-court players around these days (goes to the net no matter what after serving), the sort of player who used to win Wimbledon before the likes of Agassi and Hewitt began to in recent years. His serve was first-class and got better as the match wore on, it seemed to demoralise Hewitt as much as anything.
As to why Hewitt did so poorly, I think Hewitt is the sort of player who needs to be 100% mentally switched on to avoid suffering shock defeats like this one. He hasn't got the big strokes and massive serve that the likes of Sampras and Agassi have to get through matches on mental autopilot.
Hewitt's greatest strength has been his mental toughness and his ability for his mind to stay focussed on his tennis year in, year out, for virtually every match he plays.
But the signs are that he has been losing his focus in recent months. His French Open loss was a rather meek one, and this one was much worse. For the first time in his career, Hewitt is in a form slump and is the hunted - how he will handle these challenges only time will tell.
And one thing's for sure, Hewitt won't be the Number 1 player this year. He's lost in one hit as many points as you can possibly lose on the tour and according to the latest rankings http://sports.yahoo.com/ten/rankings is not even in the Top 10. If he doesn't match his semi-final performance at the US Open he would be struggling to be in the Top 20 at the end of the year.
