Martinez and Monk linked up at Swansea City earlier in their respective careers, and the pair still remain friends.
However, Monk admits that Everton’s form at Goodison Park wasn’t good enough - and that was what, ultimately, cost Martinez his job.
“I was sad for Roberto,” Monk said. “He’s a great guy and a really good manager, but you’re defined by the results that you get.
“What’s not helped Roberto is that at Goodison they’ve not been good enough this year. When you haven’t performed at home to the standards - and Goodison has always been a fortress - it has added pressure.”
Martinez was let go with Everton stuck in 12th place in the Premier League table.
The Toffees had won just once in their last 10 outings under the Spanish boss’ regime, and his position had become untenable.
The majority of Everton fans had turned on Martinez by the time he was sacked, with banners and chants heard against his leadership at many of Everton’s recent matches.
The Toffees took on Norwich City on the final day of the past season, with David Unsworth in charge, and they put in a much improved display which got them a 3-0 victory.
Ronald Koeman and Frank De Boer are amongst the favourites to land the Everton job now Martinez has departed.