*caveat: I'm not a 'keeper and like most people who play football even at an amateur level don't play in goal. Usually, because they don't have a clue about the right angles and even where to stand. It's why most commentary and analysis that the pros talk is utter wank when it comes to 'keepers.
With that said, ALL 'keepres average positions have moved back towards the goal-line. This is a trend that has only been recognised in the last couple of years, in fact, more or less since Lloris joined us. We are not talking about sweeping here, we are talking about when teams are defending when the oppo has pressure in our box.
It is said that reason for this has been driven by data, so now XG data is used heavily it has been reapplied as to assist 'keepers on where the biggest chances are being scored form, to combat this there is a trend across ALL 'keepers to drop back towards their line as a counter-measure to defend the "big chances".
Regarding Lloris on this, his numbers (save %) has gone up, NOT down!! He is saving more shots than at any time in his career!!!
De Gea meanwhile his numbers have regressed to a middle of the road 'keeper, nothing special nothing bad. His positioning BTW has always been one of the furthest back, further back than Lloris when he joined Spurs. De Gear a couple of years ago was posting numbers never seen before, it was thought they were freak numbers, that they couldn't be sustained over time and so that has proved to be.
Other stuff you mention about "commanding the 6yrd box" is complete and total nonsense, the ONLY voice you can hear on the pitch is his, repeatedly in EVERY game.
Every 'keeper has their weaknesses, I've never rated his distribution, but here again, the issue is more nuanced than it appears, his ball distribution is one of the best in Europe! Now a lot of this has to do with the style of play as dictated from the manager, so under Poch, we played out from the back, therefore he was on the ball more because of this. One of the reasons to playout from the back is to draw the oppo onto you, so spaces are opened up in the middle of the pitch, this will lead the oppo (should they decide) to press the receiving defenders or even the 'keeper, the law of averages says that they will nick the ball once in a while, or force the 'keeper into an error when he misplaces a pass under that pressure or worse (BTW more teams concede goals as a result of a keeper kicking long than short, but us Englanders just shout "get rid", proper football)
He's not in decline, he's never posted better numbers in his entire career. What's in decline is our defence, the more the oppo shoot the more they will score. Stop the shots, you stop the goals.
I have lost track of the number of times recently where I have said to myself and heard others say “keeper should have done better” in relation to Lloris- and he’s only played half a season. And if you think he physically commands his 6 yard box you are watching a different game to me because every time we face a corner my heart is in my mouth.( I didn’t mean he doesn’t vocally command his 6 yard box, I meant physically he doesn’t). I don’t really place much weight on stats as you appear to as they can be made to fit a particular agenda. Ok you know best. He is a keeper at the top of his game cos the stats say so!