Both Cincinnati and Pittsburgh went to the playoffs in 2015. Cincinnati won the AFC North, and Pittsburgh then eliminated them in the Wild Card round. On top of that, each team had a win against the other on the road in the regular season. Clearly these two teams are quite evenly matched. Both have lost players in free agency too - Cincinnati has lost receivers and Pittsburgh has lost players in the secondary. How does this affect the matchup between the Bengal's throwing game and Pittsburgh's secondary?
Cincinnati has lost two receivers - Marvin Jones (to the Detroit Lions) and Mohamed Sanu (to the Atlanta Falcons). Marvin Jones was the number two receiver beside A.J. Green. He made 65 receptions for 816 yards last season - an average of 12.6. Sanu was the fourth target on the roster overall - after Green, Jones and Tyler Eifert. He made 22 receptions for 314 yards last season - an average of 11.9 yards. Clearly this is detrimental to the Cincinnati passing game. By losing these two weapons, their depth has dropped drastically.
Coming to Cincinnati is Brandon LaFell (from the New England Patriots). LaFell made 37 receptions for 515 yards back in New England for an average of 13.9 yards. That's 201 more yards with only four more catches than Sanu. LaFell seems to have been an underused asset for the Patriots, but this is only a partial fix. Of course picking up LaFell is useful (whether or not he will prove as prolific as his statistics suggest will become evident at the season's start), but the Bengals lost two receivers - which still leaves them with only three viable targets down field (Green, Tyler Eifert and LaFell). This is not a great situation for Cincinnati.
On the other hand, Pittsburgh has lost two players from their secondary. Antwon Blake (Cornerback) to the Tennessee Titans and Brandon Boykin (Cornerback) to the Carolina Panthers. Losing these players to an already weak defense is not great. Antwon Blake had some good stats, believe it or not - 76 combined tackles, 1 sack, 12 passes defended, 2 interceptions and 1 forced fumble. This means that out of any cornerback, he had the most tackles and had the most pass defenses in the secondary. This is another bad loss. Brandon Boykin, who had 25 combined tackles, 1 sack, 5 passes defended and 1 interception. This is less spectacular, but damages the depth. With this duo leaving the team, it leaves Mike Mitchell as the top safety (with joint first in tackles with 80, most interceptions with 3, joint first on forced fumbles with 2 and the most fumble returns with 2 and the most pass defences of a safety with 9) and William Gay as the top corner (with joint first on interceptions as a cornerback with 2, and second most tackles after Blake at as a corner with 58), however he is 31 and so likely only has a few seasons left.
The matchup here is likely weighed in the Bengals' favor. Sure, they lost 2 players and therefore depth in the receiver corps, but they picked up LaFell, which if nothing, returned some depth. Looking to the draft, they would only have to spend one pick on a receiver to solve this issue, which may not even be their top pick. On top of all of this, they have the star that is A.J. Green - a real danger to any secondary that faces him. On the other hand, Pittsburgh will have to more heavily augment their secondary to solve their issues. In the draft, Pittsburgh will look towards cornerbacks and safeties, and will likely be forced to spend some high picks to get them. For this reason, as well as the lack of a standout out player on the Steelers secondary, this matchup is currently, and will likely remain for the season, in Cincinnati's favor.