Joe Flacco's biggest challenge is passing Ravens' critical chemistry test

Max say Kap should have Mallett's spot (1:21)

Max Kellerman thinks Ryan Mallett's performance against Washington proves why he doesn't deserve Joe Flacco's starting QB slot over Colin Kaepernick. (1:21)

OWINGS MILLS, Md. -- The good news for the Baltimore Ravens is quarterback Joe Flacco is expected to start the regular-season opener at the Cincinnati Bengals.

The bad news is that will be the first game action for Flacco in 252 days.

The Ravens announced Friday that Flacco will practice at some point before the beginning of the regular season, but he won't play in the remaining three preseason games because of a back issue. It's understandable the Ravens want to play it safe with Flacco, but this increases the challenge of Flacco building chemistry with his receivers, which is an issue this year in particular.

Flacco has not played more than 17 games with any of his top three wide receivers (Jeremy Maclin, Mike Wallace and Breshad Perriman), any of his tight ends or his best pass-catcher out of the backfield (Danny Woodhead). While practice will be beneficial, Flacco already has been sidelined for two weeks of training camp and essentially will miss four to five quarters of preseason action that could have helped in building rapport with his targets.

This isn't like past years when Flacco had an innate trust when throwing to Derrick Mason, Anquan Boldin and Steve Smith Sr. The only player on the roster who caught a pass from Flacco beyond 2015 was Michael Campanaro.

"Joe knows the offense," coach John Harbaugh said Monday. "But still, there is a rhythm and chemistry and timing and execution that, really, practice is valuable for. The sooner the better, but not before he is ready."

Flacco's history says he'll be under center when the games really count. He's missed only six games in his nine-year career, and that's when he tore two knee ligaments.

The fact that the plan is for Flacco to start the regular season also downplays the need to sign quarterback Colin Kaepernick. Baltimore likely would pursue Kaepernick if it felt Flacco was going to be sidelined for an extended period. Still, the concerns over struggling backup Ryan Mallett won't subside until Flacco suits up.

This is the first time that Flacco won't see the field in the preseason, but he was limited last year after coming back from knee surgery. Flacco played in only one preseason game in 2016 (throwing a total of 16 passes), and he went on to throw for 258 yards and one touchdown (100.3 passer rating) in the regular-season opener.

If all goes according to the Ravens' plan, Flacco will return to the practice field at some point during the next three weeks, and he'll go against one of the league's toughest defenses every day. But there will be questions about how effective Flacco will be coming off this back injury, given his recent track record.

Since being named Super Bowl MVP, Flacco is 29-29 as a starter with an 82.5 passer rating, which ranks 33rd in the league. His touchdown-to-interception ratio (1.31) is the worst in the NFL among quarterbacks who've played more than 16 games.

Flacco needs all the work and as many throws to his targets as he can get. When Flacco returns -- whatever day that might be -- he will be in catch-up mode.