The then 17-year-old from Burkina Faso caught the eye with a number of impressive performances for the club - including a man-of-the-match display against Malaysia XI and a superb goal against Indonesia All-Stars.
His countries lowly FIFA Ranking in the past (they are now in the top 50 after a good year) has made it difficult for him to obtain permission from the Home Office to play football in the UK - despite his exceptional talent.
If Mourinho had his way, they would have signed Traore to a professional contract when he turned 18 last month - but still he does not feel the eligibility criteria.
He has not been featuring regularly enough for the Burkina Faso national team - so Chelsea could not reward him for his excellent pre-season with the contract he might have deserved.
So at the moment he is still not managing to play regular senior football, despite clearly looking up to the part.
However, today, he was given the opportunity to play senior football for the first time this season - in a very important game.
He came off the bench in the 78th minute for his national team this evening - as Burkina Faso took on Algeria in a FIFA World Cup qualifying play-off. This was the first leg, played in the Burkinabe capital Ouagadougou - as the Afcon finalists aim to make history, and make it to their first ever World Cup finals.
Traore came on at 2-2 and had a positive impact. He struck a long range effort that was well saved by Rais M’Bolhi, before Aritistide Bance gave the home side a lead, 3-2 the final score.
For Traore it would have been a relief to finally get a chance of competitive football after a pre-season that offered so much promise.
Now he will hope to feature against Algeria in the return leg in November, as Burkina Faso aim to make it to the World Cup - and to give Traore two memorable summers in a row.
And by then Chelsea will hope to have finally got him a Work Permit.
image: © Jason Bagley