The Spain international spent three seasons under Emery’s management after the 30-year-old produced his best football at Valencia during the head coach’s spell in charge.
Mata emerged as a promising talent in the 2007-08 season after the attacking midfielder scored nine times in 33 games in La Liga.
Emery took charge of los Che ahead of the 2008-09 campaign and Mata went on to net 37 goals in 141 outings at the Mestalla before his move to Chelsea in 2011.
Arsenal turned to Emery as their new manager in the summer after Arsene Wenger led the Gunners to a disappointing sixth-placed finish in the Premier League table.
The north London side won 11 games on the spin in all competitions after Emery’s side lost to Manchester City and Chelsea FC in their opening two Premier League fixtures.
The Gunners won seven successive fixtures to hoist themselves up to fourth place in the Premier League table, having produced some exciting football.
Only Manchester City have found the net more times in the English top flight this season than Arsenal.
Mata, who didn’t win a major trophy under the current Arsenal boss at Valencia, believes Emery’s biggest quality is his communication skills.
“I think what’s special about Unai is the way he communicates,” Mata said in Unai Emery: El Maestro, an authorised biography of the Arsenal manager.
“In his talks, he used to write three, four or five things on the board: those were the points he was going to bring up.
“Sometimes it was five phrases or metaphors he was going to explain. I’ve never seen that with my other managers.
“They usually revolved around phrases about positivity, camaraderie, the values he wanted to create in his team.
“He communicated by means of the points he had written down.
“His talks could go on and on because he didn’t notice the time, but what he said was always intense, and he would ask you questions. It became a kind of seminar.”
Emery’s side drew 2-2 with Crystal Palace at Selhurst Park last weekend to see their 11-game winning run come to an end.
Arsenal will be able to test their title credentials when the Gunners take on second-placed Liverpool FC at The Emirates on Saturday evening.
The Gunners have a poor record against the Merseyside outfit over the past two or three seasons and haven’t beaten the Reds since April 2015.
Liverpool FC have scored 17 times in their last five meetings with Everton.
Emery masterminded Sevilla’s 3-1 win over Liverpool FC in the Europa League final in Basel in 2015.
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