??
Err, no legitimate 5.5 would be beaten by a 4.5, ever. Not even once in 50 matches. Probably would be mostly 6-0 and 6-1 sets....
Tennis is just not all about skill, there is a big psychological component and I get the vibe that this guy has a high standard deviation in his game quality and implodes once in a while.
I play a guy that reminds me very much of this guy's style (roddikish) and we usually split games. Sometimes he is just on fire and kicks me 6-0 even if I play a very consistent game, other times he really can't keep it together for even a two ball rally and has the ball flying all over.
It's hard to judge too much out just out of this footage, but like I said this guy looks like unstable 5.5
Guide:
5.0
FOREHAND: Strong shot with control, depth, and spin; uses FH to set up offensive situations; has developed good touch; consistent on passing shots
BACKHAND: Can use BH as an aggressive shot with good consistency; has good direction and depth on most shots; varies spin
SERVE/RETURN OF SERVE: Serve is placed effectively with the intent of hitting to a weakness or developing an offensive situation; has a variety of serves to rely on; good depth, spin, and placement on most second serves to force weak return or set up next shot; can mix aggressive and off-paced service returns with control, depth, and spin
VOLLEY: Can hit most volleys with depth, pace, and direction; plays difficult volleys with depth; given opportunity, volley is often hit for a winner
SPECIAL SHOTS: Approach shots and passing shots are hit with pace and a high degree of effectiveness; can lob offensively; overhead can be hit from any position; hits mid-court volley with consistency; can mix aggressive and off-paced service returns
PLAYING STYLE: Frequently has an outstanding shot or attribute around which his game is built; can vary game plan according to opponent; this player is 'match wise,' plays percentage tennis, and 'beats himself' less than the 4.5 player; solid teamwork in doubles is evident; game breaks down mentally and physically more often than the 5.5 player
5.5
This player can hit dependable shots in stress situations; has developed good anticipation; can pick up cues from such things as opponent's toss, body position, backswing, preparation; first and second serves can be depended on in stress situations and can be hit offensively at any time; can analyze and exploit opponent's weaknesses; has developed power and /or consistency as a major weapon; can vary strategies and style of play in a competitive situation.
We really cannot judge this accurately without seeing him in a competitive match - mine is just a guess, but he is definitely somewhere between these two.
P.S. He takes his racket back for a backhand with face completely up like I used to sometime ago - bad habbit, not too bad though.