One, Baalke and Harbaugh wanted to add speed and explosiveness to the offense and they have. Jenkins and James are similar in that they have long speed and return ability.
Second, the Front Office is completely confident in the offensive linemen they already have in Kilgore, Boone and Person. It appears that they are not focused on getting anyone else to fill the RG spot. If anything, they may look to UDFA's to bring in some competition on the offensive line.