The Spain international is one of the two outfield players along with Nacho Monreal to play every minute in the Premier League for the north London club. Arsene Wenger has mainly deployed him in the right wing-back position, but he is yet to register an assist or score a goal in the league.
Bellerin was dubbed as one of the best right-backs in England's top flight club competition. His fine display for the Emirates club over the last few seasons forced Mathieu Debuchy out of the starting XI.
Barcelona considered re-signing him in the summer transfer window. However, Arsenal were reluctant in letting the defender leave. The Catalan club completed the signing of Nelson Semedo from Benfica in the same window.
The 22-year-old started for Arsenal in their goalless draw against West Ham United. Cascarino stressed that Bellerin failed to offer, both in terms of attack and defence. The former Celtic striker also went on to claim that Ainsley Maitland-Niles, who started as a left wing-back offered more against David Moyes' side.
"I don't know what has happened to Héctor Bellerín, who has really gone backwards for Arsenal. He was touted as one of the country's best right backs, supposedly wanted by Barcelona, but he hardly got a kick in the first half last night," Cascarino told The Times.
"He was offering very little in attack and he was caught out defensively on occasions. We often question Arsène Wenger's development of young players at Arsenal, and this could be another piece of evidence against the Frenchman.
"The contrast was stark between Bellerín and Ainsley Maitland-Niles, who was so much more effective at left back."
Meanwhile, Cascarino was in full praise of Wilshere, who made his first Premier League start of the season against West Ham.
"Arsenal have been a bit ponderous in recent games, slowing down attacks and allowing their opponents to get back into shape, so the return to the starting line-up of Jack Wilshere last night helped them in that regard," he said.
"Wilshere, right, will always try to do things quickly, delivering first-time passes to team-mates ahead of him.
"He will often take a touch that controls a pass and takes the ball beyond an opponent. Last night was no exception. While Granit Xhaka was making little impact alongside him in the centre of midfield, Wilshere was pulling all the strings for Arsenal."