Don't forget #1 - Damian Williams (ex Tennessee Titans and USC WR). He is still just 26 and has 106 NFL receptions and 1313 yards (he averages 12.4 yards/ reception) over his 4 seasons in the NFL. He is playing for his career and he is a real chance to take the PR/KR duties over Thigpen. He is also one of the highest character players in the NFL and you know that Joe and Dennis Hickey will lap that up.
Tennessee gave up on him due to unavailability re injuries but if healthy, he has talent and is a decent route runner. He has also looked good so far at training camp. If fully healthy, I can see him passing Thigpen and Matthews.