The 23-year-old has issued a rallying cry following a terrible first half of the season that sees the club sat in 15th position ahead of their clash with Betis on Monday
A disastrous season sees the club sat in 15th spot ahead of Monday's clash with Betis, with the Basque side struggling to replicate their form from last term.
The continued marginalisation of striker Fernando Llorente by coach Marcelo Bielsa has also provided a running backdrop to the campaign, with Herrera issuing a passionate rallying cry.
"We're either united, or we won't turn it around," he told reporters after training.
"This league is very equal with the exception of Barcelona, Atletico and Real Madrid. We have to be united because we know anyone can beat anyone.
"We can't let a single weekend pass without being united, being more 'Athletic' than ever and showing we can do it."
When asked about the cause for the slump, that has seen the club slip down the Liga table and crash out of the Europa League and Copa del Rey, the 23-year-old stated his side must simply look for "solutions" to their problems.