The reasoning doesn't seem to be production, but blocking. That being said it makes total sence, what we have right now is 3 pass catchers who aren't that very good at blocking. It was the #1 reason behind the reluctance to play Gregg Guenther. I wouldn't be surprised if this decision was based around the fact that they wanted Ben Troupe as a #1, but his blocking isn't good enough for that - so they, again, have to keep 4 TEs on the roster or lose Gregg Guenther.
"I had four candidates who I would have been very happy with, but I felt like Coach Zernhelt, I just had the gut feeling that he was going to help us the most only because of the vast experience he has on the offensive line. When you look at the tight end position, he’s an extension. He lines up next to the tight ends. So much of his play is dependant on technique and offensive line technique. We showed this year that we can get all of our tight ends down the field and catch the ball, but what we need to do is become better blockers and so on and so forth. John had a year of experience in the NFL with Mike Heimerdinger with the Jets last year. Talking to people there and watching the tight ends improve throughout the season, I felt like he was the best candidate."- Jeff Fisher
http://www.titansonline.com/news/newsmain_detail.php?PRKey=3647
"I had four candidates who I would have been very happy with, but I felt like Coach Zernhelt, I just had the gut feeling that he was going to help us the most only because of the vast experience he has on the offensive line. When you look at the tight end position, he’s an extension. He lines up next to the tight ends. So much of his play is dependant on technique and offensive line technique. We showed this year that we can get all of our tight ends down the field and catch the ball, but what we need to do is become better blockers and so on and so forth. John had a year of experience in the NFL with Mike Heimerdinger with the Jets last year. Talking to people there and watching the tight ends improve throughout the season, I felt like he was the best candidate."- Jeff Fisher
http://www.titansonline.com/news/newsmain_detail.php?PRKey=3647