Not sure of that excuses it..
I'm not sure if Krul would have done better on the corners, but Harper surely doesn't command his area well enough. He's not the tallest and has lost whatever spring he had, meaning he's not only vulnerable on the ground but also in the air. The only thing still on par for a Premiership goalkeeper is his reflexes. He did make some good saves too, but there's no denying we've lost valuable points in Krul's absence.
I'm not sure how you can say he's better than Elliot too. The latter has been fairly solid this season after a shaky start and has age on his side. There's still a chance he could be a reliable back up for years to come.
Not trying to excuse it, just that all keepers make mistakes like that(especially when defenders couldn't be arsed to make themselves open to pass to). I don't think Krul would have did too much better at saving many of the goals the past few games.
It's pathetic the way people go on, every goal Harper concedes, many people seem to blame him for it.
Elliot has looked poor in all games for us part from the last two, I do see Harper retiring very soon though.