Spelling a man's name right is not only respectful, it helps to avoid confusion. There's a big difference between "Tom Dork" and "Tom Doak."
As for Thomas, if you want to look at the evolution of his style, I think it makes sense to lay out all of the work he did before passing judgment:
1908 - Whitemarsh Valley (PA) - course later worked on by Flynn and Ross
Unknown Date - Marion (MA)
1910 - Spring Lake (NJ) - course later revised by Tillinghast
1920 - Los Angeles North (CA) - with J. Neville and Herbert Fowler
1921, 1923 and/or 1926 - Griffith Park (CA) - existing course built by Bendelow
1921 - Red Hill (CA)
1921 - La Cumbre (CA) - existing course built by W. Watson and Bendelow
1924 - Palos Verdes (CA) - with W. Bell
1925 - Ojai Valley (CA) - with W. Bell
1926 - Baldwin Hills (CA) - with W. Bell
1926 - Bel-Air (CA) - with Neville and Grant
1926 - El Caballero (CA) - with W. Bell
1926 - Fox Hills (CA) - with W. Bell
1926 - Saticoy Regional (CA)
1927 - Riviera (CA) - with W. Bell
1930 - Stanford (CA) with W. Bell
Other influences:
Worked in Philadelphia until 1907 - was exposed to all of the great courses existing in that area at that time
Philadelphia Cricket - witnessed the reconstruction of the existing course by Ross
Philadelphia Cricket - aided in the construction of the new Flourtown course designed by Tillinghast
Sunnybrook - connected with the construction as influenced by Ross
Merion/Philadelphia Municpal - exposure to H. Wilson's design philosophies (Wilson also wrote Thomas with advice on his first CA course)
Pine Valley - member and watched the construction, assisted Flynn in 1928 with modifications
Served as a Captain in the Army Air Service during WWI - if overseas would be interesting to know if he had exposure to any courses
Moved to California after WWI - exposure to all of the existing courses in the area
So what does that tell us? Thomas had seen many of the great courses in existence before he designed his masterpiece at Riviera. A smart, yet possibly eccentric, man, he would have learned and absorbed a lot from the likes of Ross, Flynn, Wilson and Tillinghast, and perhaps even learned something from seeing some of Bendelow's work. One could extrapolate that by the time Thomas moved to California he may have also been influenced by the likes of Findlay, Emmet, Jack Reid, Willie Dunn, Loeffler, Willie Park, W. Campbell and Travis, amongst others.
After his move to California, Thomas probably adapted his style to the ground found on the west coast. So its conceivable that many of the machinations that worked well on the east coast may have been altered when he started working with a new canvas. One would venture that Thomas would have learned a bit from the work previously done by Willie Watson, Fowler, MacBeth, Nicoll, John Dunn and Reid to name a few, and from his contemporaries such as MacKenzie, Neville, Grant, Behr and O'Neil. A smart man, he would have viewed the good and the bad with the same critical eye while figuring out what worked and what didn't.
My guess, Thomas was influenced by his entire resume of experience with golf courses, picking up bits and pieces here and there while developing a style that emphasized a memorable experience on every hole and the creation of situations of choice for the player. He was a well-educated man with a depth of exposure to the great golf courses of his era and the work of the great (and not-so great) architects that had preceded him. His opinion was sought out on projects on both coasts, and from his correspondence it is evident that others not only sought his council but also shared their ideas with him.
To say Thomas adopted a style from any one architect is moronic.