The Jaguars needed receiver help after Justin Blackmon was suspended.
Taylor will actually benefit the Jaguars twofold. One is the fact that he is a receiver and can catch the ball. The other is the role of scout. The Cardinals play Jacksonville in Week 11. That signing is likley every much about Taylor's talent as it is about getting information from him.
League rules allow a team to sign a player from someone else's practice squad, but not the week you play. The Jags would have been unable to sign him next week.
Coming out of training camp, Taylor appeared to make final cuts, then did not. He was signed to the practice squad. Then he was promoted when Larry Fitzgerald was hampered by a hamstring. He caught three passes for 40 yards while on the 53-man roster.
Later, when the team promoted receiver Brittan Golden, he was cut and then re-signed to the practice squad.
Arizona could have promoted him to keep Jacksonville from poaching him, but with six receivers already on the roster (Fitz, Andre Roberts, Michael Floyd, Jaron Brown, Golden and Teddy Williams), they elected to let him go.