18 minutes a game is absolutely not top 4 minutes, this argument suggests that Luca Sbisa is a top 4 guy.
As for the 6 game sample size I've already answered this, these numbers are not representative of anything as a number of those games went to multiple overtimes causing an inflation in TOI.
First you completely ignore that he averaged top pairing ice time in the only time the Panthers made the playoffs in his career. Is it because if he wasn't considered a top 4 D-man by Florida, he wouldn't have gotten that ice time and thus it doesn't help your narrative?
How is 18 minutes a night not top 4 minutes? I guess that means Chris Tanev isn't the top pairing d-man us Canucks fans think since he averaged 21 minutes the last 3 seasons. I guess that means he may barely be a top 4 D-man in your opinion since i'm guessing the minimum a top 4 should play is 20 min.
You do realize that theres only 60 minutes in a hockey game right?
Top pairings average 24-28 minutes
2nd pairings average 18-20 minutes
3rd pairings average 10-15 minutes
Luca Sbisa's career in Vancouver (not including this season where he averages 15 minutes) he has averaged 17 minutes. Thats between 2nd and 3rd pairing minutes which makes sense seeing how injury depleted the d has been in his time here. Not to mention the fact Jim Benning thouht he was a top 4 d-man when he first brought him here so they originally tried to play him as one.
Luca Sbisa's ice time has been going down every season since coming to Vancouver (last 3 years including this season). Erik Gudbranson's ice time has gone up every year his last 3 years in Florida. His ice time here is almost at the highest he has ever had, being under a minute less.
4 years ago Gudbranson averaged almost 19 minutes a game. a 20 year old does not get that much ice time unless he is absolutely considered a top 4 d-man.