The QB thing is really hit or miss. But every now and again you get the perfect storm, like the QB class of 1983, where 3of the 6 QBs selected in the first round were astounding and a couple of the others reasonable (Elway at #1, Dan Marino, Jim Kelly, and lesser but still pretty good Todd Blackledge and Tony Eason). And even though Marino was taken after Blackledge, it was considered shocking, since everybody thought he would be taken higher.
Or the class of 2004, where the first three QBs selected were Eli Manning, Ben Roethlisberger, and Philip Rivers.
And in those kinds of years, you really do want one of the first few picks. The problem is you can’t predict those types of years happening.
Also, the NFL is one of the worst places to find tanking on purpose. The incentives aren’t there. Coaches and players are regularly fired after losing seasons, so they have no reason to make their employment position worse, even if the front office and ownership wants it.
Look at the “Suck for Luck” campaign. The Colts won 2 of their last 3 games to finish out the 2011 season and put themselves in jeopardy for getting the first pick. The end of a season is the absolute worst time to start winning games if they were deliberately tanking. And following the season, the coaching staff, front office, and most of the roster was gutted. If they were deliberately tanking, they did it the wrong way.