I remember them playing really good football in at least one of the seasons. There was no expectation of Liverpool at that point, like there is now. Look at the team they had when Klopp took over and you'll see that they weren't anywhere near what they are now in terms of playing staff.
The season they finished 2nd, sure. But that's the point, 1 good showing out of 4 is not a great return.
If he'd estabished them as a top 4 side, maybe reached the CL knockouts, I'd rate the job he did a lot higher. I don't think failing to win the league should be held against him, but the overall body of work isn't that strong.
In fairness, he's never had a squad as good as we have now or this much money, and he's likely a better manager now than he was then, so it wouldn't be a complete surprise if he did a good job here. But if the board believes him to be the stand out candidate in world football, that is very bizarre.