Correct Roman Gabriel requested the trade because he did not want to battle Hadl for the number one QB. Now the rams acquired Hadl because Gabiel was hurt in 1972 because of that the Rams had to trade for Pete Beathard so the Rams wanted two good QB's in 73, but Gabriel requested to be traded so the Rams dealt him to Philadelphia for WR Harold Jackson and then singed James Harris to backup Hadl.
Interesting fact is the Rams traded three high profile Quarterbacks to the Eagles, Norm Van Brocklin, Roman Gabriel & Sam Bradford.