UFC Fight Night 73 (Dillashaw vs Barao 2, Chicago) Ticket Sales must be slow. Groupon Deal Available.

Ticket sales must not be going well for UFC Fight Night 73, Dillashaw vs Barao 2, on 7/25/15 in Chicago. Groupon has a deal listed with tickets for the following prices:

$53 one for yellow-section seat
$78 for one purple-section seat
$93 for one red-section seat
$128 for one green-section seat
$178 for one pink-section seat
$253 for one floor or orange-section seat

Here’s the full card:
TJ Dillashaw (11-2) vs. Renan Barao (33-2)
Miesha Tate (16-5) vs. Jessica Eye (11-2)
Myles Jury (15-1) vs. Edson Barboza (15-3)
Joe Lauzon (24-11) vs. Takanori Gomi (35-10)
Eddie Wineland (21-10-1) vs. Bryan Caraway (19-8)
Gian Villante (13-5) vs. Tom Lawlor (8-5)
Daron Cruickshank (16-6, 1 NC) vs. James Krause (21-7)
Ramsey Nijem (9-5) vs. Erik Koch (14-4)
Rustam Kabilov (17-3) vs. Danny Castillo (17-8)
Zak Cummings (17-4) vs. Antonio Braga Neto (9-2)
Kenny Robertson (15-3) vs. Ben Saunders (18-6-2)
Jessamyn Duke (3-2) vs. Elizabeth Phillips (4-3)

Why are the ticket sales slow? Lack of higher weight classes? Lack of interesting fights?