Alonso joined Chelsea from Fiorentina last summer and starred as left wing-back in Antonio Conte's historic title-winning side.
The Spaniard had two previous spells in the Premier League with Bolton and most recently at Sunderland and was considered a surprise signing by Conte.
But Wilkins believes he has worked hard on his game and physique during his time in Serie A and has compared the situation to Matic.
Matic left Chelsea to join Benfica in 2011 but was re-signed three years later for around £21million and has become a vital part of the Blues' midfield.
Ray Wilkins has compared Marcos Alonso's Chelsea form to when Nemanja Matic returned to the club Chelsea wages: Which stars earn the most? Thu, March 9, 2017
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Nemanja Matic was exactly the same as Marcos Alonso, Matic was in the reserves at Chelsea
Ray Wilkins on Chelsea star Marcos Alonso
"He came back and now he's performing okay.
"Matic was exactly the same, Matic was in the reserves at Chelsea.
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Ray Wilkins believes Marcos Alonso left the Premier League and returned a better player like Matic
"He was half the size, he was a skinny languid sort of guy.
"He went away to Benfica, came back double the size and that was because he was playing week in, week out.
"He come back and he's performed miracles."