The Teessiders are now seven points off the top six with seven games to play, while manager Neil Warnock has admitted his side’s promotion hopes are as good as over.
Boro managed to draw level at the Vitality Stadium after Duncan Watmore cancelled out Philip Billing’s opener, yet second-half goals from Jefferson Lerma and Dominic Solanke proved costly.
Defender Dael Fry and midfielder Marcus Tavernier both missed the match through injury – with supporters quick to point out their absence.
Here’s how some reacted on social media:
@JezBathNBeyond: As #BORO look towards next season the evidence is pretty clear. Clean sheets when @Daelfry1 is playing. Massive holes when he isn't. If we're to make play-offs next season we either need him playing every match or to bring in someone who can fill the sizable hole he leaves.
@Chris_Garbutt87: One thing I never thought I’d call a Warnock team is spineless. You’d think they were on holiday today.. fighting to get in the top six?
@smoggyontour86: Sell Dejan, leave Betts to find another club, Boro need to go out and find a top quality keeper and a striker who can score goals. Massive job for Warnock.
@chrisrobson13: Biggest game of the season and we didn’t show up…
@benoliver000: Season over, onto the next
@Steptoesyard: Given the attacking options brought into the club in January it's been massively underwhelming.
@MikeBrownGaz: We're only half a team without Fry and Tavernier
@jackallisonnn: That’s nothing against McNair or Hall but I feel like both of them play better with Fry next to them
@GraemeBandeira: After today’s stroll along the pier I’d be surprised if we got another win. Season ended months ago tbh because of too many performances like today. Quicker the season ends officially the better and we can start shifting the rubbish to the tip.
@twofootanidol: It’s the hope that gets you in the end , inconsistent, hot , cold , you just didn’t know which Boro were going to turn up