You raise a good point; what is the average save rate for Prem ‘keepers? Is it 12%? And how far off this is Sanchez?You can usually see through body language, positioning, eye movement etc. where they're going to put it. The PK taker is always going to have the advantage, but you can hike that normal 12% save rate up to 20-25% if you really put effort into it.
The value is so low though, one or two saved pens per season, that I can't imagine many keepers putting much effort into it.