I think that @Troy is mostly correct concerning Shawn’s picking technique. There are a number of examples in Power Licks and Power Solos which are strongly indicative of downward pickslanting, however, there are a few odd cases which I don’t feel Troy has addressed.
Shawn definitely states that he starts his ascending and descending 6s with an upstroke, which is indicative of DWPS. The descending 4s and 5s lick, which I’ve tabbed below (in a symmetrical shape), is also indicative of this.
-9-7-6---7-6-------|-------------------|-------------------|
-------9-----9-7-6-|-9-7-6---7-6-------|-------------------|
-------------------|-------9-----9-7-6-|-9-7-6---7-6-------|
-------------------|-------------------|-------9-----9-7---|
-------------------|-------------------|-------------------|
-------------------|-------------------|-------------------|
u d u d d u d u d u d u d d u d u d u d u d d u d u
The string changes in this example are particularly indicative of DWPS. Shawn also ends this sequence on an upstroke, which is a common tendency when using DWPS. Interestingly, Shawn calls this a “strict alternate picking” lick, which it is not.
As Troy mentioned, Shawn says that he can’t play this lick beginning on a downstroke, calling it a “disaster.”
I do wonder, however, if some part of this “disaster” is a consequence of an issue with chunking. Adherence to the DWPS method allows the 9 note sequence to be chunked as a single unit, which is easily executed and easily repeated. Playing a sequence of odd length with strict alternate picking would require that the sequence be composed of two separate chunks, one beginning with a upstroke and one beginning with a downstroke. Repeating the sequence then requires flip-flopping between the two chunks, which I feel is probably more difficult than repetition of a single chunk.
There are also some interesting outliers, which don’t fit the DWPS methodology. For example, in Power Solos, Shawn demonstrates two different sequences for playing descending pentatonic fives.
The first of these is as follows:
-15-12----------|-12-------------|
-------15-12----|----15-12-------|
-------------14-|----------14-12-|
----------------|----------------|
----------------|----------------|
----------------|----------------|
d u d u d u d u d u
This is a strict alternate picking sequence, and Shawn burns through it. If it’s played with linear picking movements and DWPS throughout, this would require a 2-string swipe between the two groups of 5. An alternative is that Shawn may have included some wrist extension on the final note of the first group of 5, allowing him to jump the two strings before beginning the second group of 5 with the upstroke.
I’m not sure which of these approaches is being used. Shawn demonstrates this sequence very quickly, and with the angle on Power Solos, I can’t determine if any wrist extension is being used at all. Also, Shawn demonstrates with his usual wet lead tone, which has delay and reverb, and could potentially mask any sound that might indicate swiping.
I think Shawn probably used both approaches, depending on tempo.
The second of these sequences for descending pentatonic 5s is:
-15-12----------|----------------|
-------15-12----|-15-12----------|
-------------14-|-------14-12----|
----------------|-------------14-|
----------------|----------------|
----------------|----------------|
d u d u d d u d u d
This is the standard DWPS arrangement of descending pentatonic 5s, as played by Eric Johnson, further indicating that Shawn was at least primarily a downward pickslanter.
Shawn’s picking movements are interesting, also. Shawn’s medium to fast picking seems to be primarily driven by wrist deviation, though there is certainly some rotation and flexion/extension visible at these speeds. This suggest to me some degree of crosspicking and 2WPS.
Shawn’s super fast picking looks qualitatively different to me. To me, this looks a more constant DWPS orientation with a primarily elbow driven picking movement, with some deviation-like movement of the wrist occurring because the wrist is so relaxed, whipping back and forth due to the primary elbow movement. Based on Troy’s analysis of Jorge Strunz’ technique and Shawn’s very shallow pick depth, I suspect he incorporated significant swiping when utilizing this mechanic.
Unfortunately, it’s difficult to be really concrete about much of this. There is little high quality video of Shawn available. Of the videos which are of sufficient quality, most provide poor angles for studying his picking movements. Shawn almost always wore long sleeves to cover his ever worsening psoriasis and his increasing weight (due to Cushing’s Syndrome) obscures his movements in some of the videos shot near the end of his life.
Still, I feel I can justify the existence of the elbow mechanic. Consider the atonal outro jam in this video of Not Again.
Shawn’s atonal solo begins at 4:08. Initially, he plays mostly legato phrases, with some medium to fast picking. We have an angle down the neck, and we can see that the picking movement is based on wrist movement, with very little movement of the forearm. To my eyes, this looks like to be primarily wrist deviation, but with some rotational and flexion/extension movements also.
Beginning at about 4:56, Shawn begins playing some extremely fast picking licks. To me, this looks very different from his primary medium to fast speed form. Here, it looks to me like the forearm itself is moving up and down due to a small elbow movement, with the wrist loose. Shawn is wearing black and the movement is difficult to see, but I’m convinced there is a change in movement mechanic happening here. When I slow down this video in Transcribe!, it still appears to me that this super fast movement is primarily elbow driven.
Perhaps the change in picking mechanic is more evident in this video:
Shawn begins a solo, with a decent view of his picking hand at about 36:00. Initially, this looks to me like the medium to fast speed, wrist based picking movement. Notice that there is not much movement of the sleeve over his right forearm. At about 37:00, Shawn begins the super fast picking movement.
Notice the much greater degree of movement of the sleeve over his right forearm, and over his upper arm. I don’t feel this much greater amount of sleeve movement would be consistent with the same wrist movement at higher speed. Instead, this indicates a change in picking mechanic to me, with the elbow being the primary driver of the picking movement.
I’d appreciate if others would comment on what they believe is happening here. Most seem to believe that Shawn exclusively used picking movements which were primarily driven by wrist movement, whereas I believe that he primarily used such movements with the elbow taking over for sustained picking at super fast speeds.