Question about one of Israel's finest

Hi there.
I transcribed a LONG 234bpm pure alternate picking of the blazing Omri Zelig, one of
the best guitar players in Israel.
Here’s a link to the video:

It’s the ascending phrase that starts at around 20 seconds
And if you want another view, here he plays it after around 1:34

And here’s the tab I wrote

My question is:
In the tab, I divided the phrase to quarter notes (4 sixteenth notes in each).
I emphasized the string changes, which are NOT consistent:
The first is after an Upstroke, then D, U, U, D.
How does he do it with so fluently (what appears to me) CONSISTENT ELBOW technique, in which
upstroke string changes suppose to not work that well?