It’s easy to predict that, without Lionel Messi, even for just a couple months, the 2015-2016 Barcelona season may be in jeopardy of falling short of expectation, nevermind silverware.
The blunt truth is, with or without Messi, Barcelona was never likely to brandish any trophies this season anyways. The first indication of course was the transfer ban placed on the club until January of 2016, meaning this past summer they were not able to acquire any new players ahead of the 2015-2016 Barcelona season.
Why is this bad, even after winning the treble? The departure of Xavi Hernandez for one was a huge blow. After 24 years at the club, he departed for AL SADD in Qatar, leaving the midfield orchestrator role open.
Andreas Iniesta is surely as good as Xavi for that position, but at 31-years-old, he too is starting to enter his twilight years as a professional footballer. The Barca youth academy has helped produce some quality first team players for this season in the likes of Sandro Ramirez and Munir El Haddadi; however the two youngsters are still very much unproven at the top level and will find trouble playing against the likes of more experienced teams such as Real Madrid, Atletico Madrid, and Sevilla (just to name a few).
Already with two losses this season, Barcelona are playing catch-up. Even Luis Suarez admitted recently that they are not as strong as they were last season, and it's only October. With almost no depth on their bench aside from youth players, an injury to Messi almost becomes a moot point. Even with one of the best ever players and most prolific of goalscorers, if you do not have the necessary support around him in the form of a full, strong squad, he becomes worthless. With the weakest defense and midfield they've had in over a decade, it is very easy to say that even with Messi playing, winning any trophy this season would be an incredible accomplishment.
Pretending for a second that Messi were at full strength currently, he'd still be facing the next 10 games or so of the 2015-2016 Barcelona season without Suarez, Iniesta, Rafinha, and Vermaelen – all critical players in the starting XI. The fact that Barcelona do not have comparable replacements for these players leaves them between a rock and a hard place. Even with the arrivals in January 2016 of Arda Turan and Alexi Vidal from Atletico Madrid and Sevilla respectively, they will be entering an entirely different system of football and will require time to adjust. This is not the team from last season, they are not nearly the same threat.
Injured or not, Lionel Messi never seemed odds on for major trophies this season given the lack of experienced players around him. The 2015-2016 Barcelona season for the Blaugrana faithful will prove to be one of hardship. Maintaining a Champions League position for next year should be their foremost goal.