The Senators returned from their week-long bye on Jan. 18 but the break seems to have done more harm than good.
Taking a 3-0 loss to the Blues on the tail end of a back-to-back Tuesday, Ottawa is riding a four-game losing streak since returning from the break. The Sens went into the bye on a high note, claiming a 4-3 win against the Maple Leafs on Jan. 10.
Ottawa hasn't reached the win column since.
Craig Anderson saved 38 of 40 shots against St. Louis but his team's offence couldn't generate any finishes. The Sens have now managed just five goals in their last four games.
Ottawa sits second-last in both the Atlantic Division and the Eastern Conference standings, with a dismal 39 points that situates them above only Buffalo.
Though back-to-backs are always a formidable challenge, the Blues dominated a struggling Sens team that hasn't been producing through the second half of January.
Ottawa will have one day to recover from the loss to St. Louis before facing the Bruins on Thursday on home ice.