He'll get time. This time next season is easily enough to determine if he's worth continuing with.
The players he inherited were capable of very good attacking football. They just needed the defence sorted. Obvioulsy that's proven beyond Koeman's abilities, so we demolish the whole lot and bring in players (over valued) he thinks can get us a trophy or up the league to top 5.
We shall see.......
They weren't though. Martinez attacking play was based on over committing players forward. So it had a detrimental effect on the defence, hence why teams would suddenly look like they'd score as soon as they won the ball back by their own penalty area. It still wasn't good enough to break organised sides down though, teams had well and truly worked us out.
The whole squad needed ripping up and rebuilding and that's what Koeman is doing. I agree he seems to be trying to make us hard to beat first, but is that a bad thing? We've had average athletes who weren't anything special technically for years,
Moyes built a team around them, but you can't compete on a football level against better technical players trying to match them. I like that Koeman is bringing in different styles of player and trying to make us tough to break down. A midfield pairing of Gueye and Schneiderlin should make us difficult to break down.
Let's hope he can bring in someone who can offer something a bit different further forward now.