Steve Smith Sr. missed practice on Thursday and seems very doubtful to suit up for the Baltimore Ravens Week 5 matchup against the Cleveland Browns. Smith Sr. is currently dealing with four microfractures in his back.
No timetable has ever been given for Smith Sr.'s return to the football field, but it seems highly likely that he'll be out for at least a couple weeks. I wouldn't be surprised if the Ravens kept him out of action until after the team's Week 9 bye.
Quarterback Joe Flacco has every excuse to be struggling in the passing game. Without Smith Sr., he has nobody noteworthy to through the football to. Kamar Aiken and Marlon Brown will be listed as the starters if Smith Sr. can't go, but I'd strongly advise you to stay away from starting any of the Ravens receivers.
Although he was just recently acquired, receiver Chris Givens is worth keeping an eye on. However, it may take him several weeks to learn the playbook.
Obviously the absence of Smith Sr. also hurts Joe Flacco's fantasy football value. You'd be better off starting Blake Bortles (vs. Bucs) or Nick Foles (vs. Packers) in Week 5 until Flacco proves he can have success in the passing game without Smith Sr.