Is Lopetegui really all that or are we just getting excited because he's managed some big clubs? He was sacked by Porto after winning no trophies, he was sacked by Spain after pissing off the Spanish FA, sacked by Madrid after bad results and now it's not going too well at Sevilla. Plus, the reports are that his football is a bit uninspiring with a lack of goals.
I'm not trying to be knob, this is a genuine question btw as I think the only time I have watched one of his teams was when we lost in the Europa League.
Can't comment on Porto as I don't know much. The Spain sacking was because he spoke to Madrid about taking over after the WC. At Real he was changing the style of play but wasn't afforded the time to implement his plan as they expect instant results.
At Sevilla he took a team who finished around 6th-7th for the previous 5 years and finished 4th 3 times consecutively including winning the Europa League. The style is slower paced possession heavy rather than outright defensive, they weren't free scoring but I wouldn't say lacked goals, they averaged 1.5 goals per game across his tenure. A target we can only dream of currently.
They sold the cornerstone of his team off and replaced them with significantly worse players which is partly why this season has been poor but he's also coming to the end of cycle, 3 years is a long time for a manger imo.