When you're a big free agent, teams really try to woo you, they wine and dine you...they really sell you on the perks of playing in that city, with that organization...Testing the market implies they don't know what other teams are willing to pay. I have a hard time believing that.
It's not like a video game where teams bid on players like an auction, ya know? There's more to it than that. Maybe Letang has some stuff he wants to do post-career, or whatever...
There's just a little bit more to it than getting a contract offer faxed over to you...
And, really, you don't know exactly what you can get in a pressure situation. On noon on July 1st or 13th or whatever it is, you don't know what happens...Drew Doughty suddenly retires or demands a trade out of the blue, well, ok, we can do 4 yrs, $10.5 mil per for Letang now. It's not always so obvious...it definitely can be, but not looking around can cost you some money (similarly, looking around can cost you too...like it did for Anthony Duclair, for instance - but that wouldn't happen to a player of Letang's caliber. There's only like three people on the planet that don't realize what an incredible player this is haha)