OK, so Spurs have signed Janssen officially for £18.8m. Slightly more expensive than the standards of usual spurs signings, but still incredibly cheap given what we've seen others go for this window already. I think they signed Son for more money than him, but Son came from a club which offered him CL & with a bigger stature than AZ. Son was kinda more proven in the more competitive Bundesliga too.
Regarding Jansenn, it can go either way. But it has the potential to turn into one of the signings of the summer. The way he plays is based a lot around converting half-chances into goals, similar to Harry Kane. He has a pretty good physical presence, but also is dangerous with the ball at his feet and two-footed. He scored 32 goals in 46 games for AZ, but the standard of defending in dutch league is nothing to be proud of. It would be interesting to see how much game-time he gets next season on PL games. He is a young player & playing regularly would be crucial for his development.
I am surprised Wenger did not go for him, £18.8m is not much for Arsenal. He likes signing these kind of players & Arsenal are crying out loud for a striker. Maybe the pressure from fans is getting to him & making him afraid to gamble on a young striker? Imagine if Janssen replicates his form from the Dutch league and turns into another Suarez/RVP kind of player? Would we hear Wenger tell everyone he knew about Janssen & almost signed him? Also, Arsenal fans are a crazy bunch, if Janssen turns into a world class striker they would jump on Wenger's back for not signing him & letting him go to spurs.