That's because they're already expected to sit most of their starters with several other players likely missing the game due to injury. Among those not expected to play due to injury is Emmanuel Lamur, who will miss his second-straight preseason game due to a hamstring injury.
Lamur originally suffered the injury in the second week of the preseason against the Buccaneers and then missed the following game versus the Bears. Because the team only held closed practices this week, we don't know if Lamur was able to practice and if they're simply holding him out as a precaution, or if this injury has kept him out of practice as well.
Also missing tonight's action is defensive end Michael Johnson. He has yet to practice since spraining his MCL early in training camp. The hope is he'll be ready for the regular-season opener, but not having practiced in almost a month doesn't bode well for that happening. The good news is, with MJ out, players like Chris Carter and Margus Hunt have gotten more playing time to solidify their worth on the final 53-man roster.
The Bengals also announced cornerback Brandon Ghee, running back Rex Burkhead, cornerback Leon Hall, and linebacker Vontaze Burfict are not expected to play. Ghee being out doesn't help his chances of making the final roster. It's unknown if Hall and Burkhead are being held out due to injury or other reasons.
As has been said, don't expect many starters, if any, to be playing tonight as the Bengals look to keep their health intact with the regular season just 10 days away.