As far as goalkeepers are concerned, that's actually not very true these days, due to the way modern balls move. There has to be a degree of positioning, but reflexes, diving (or acrobatics as you like to call it), reactions etc. are extremely important and prevalent. It's not even like the balls of the 90's that you could bend or swerve. These balls are going left then right, up little then back down again, and then doing the conga before they reach the goalkeeper, and a keeper needs to be able to react to this.
Jak's been good, and unquestionably has improved, but Marshall has proved himself beyond doubt in the Premier League.
An ounce of sense and a pound of nonsense. Yes positioning is important and I fail to see how you exclude Jak from having that ability. Yes, some of his defensive work is by punching and it can lead to problems, but that can easily be offset by the fumbles and deflections trying to take possession can produce. Or mistakes like throwing it into your own net. You seem to be saying that making fantastic, instictive diving saves are a failure of positional nous, rather that a great athletic reaction to the ability of an attacker being able to place a ball or an unforseen deflection. I have rarely come across anything more foolish. You say top class goalkeepers don't make many of these saves - really? You call folk with a different opinion to you clueless then go on to be a perfect example yourself.