The failure to reach the play-offs will raise questions over the 39-year-old's future at Swansea, with the Portuguese having openly admitted his desire to manage in the Premier League.
Ironically, Gus Poyet, now manager at Brighton, who was a red-hot favourite to take charge of Swansea last summer before being pipped to the post by Sousa, was at Sunday's draw.
He witnessed a typical dominant performance by the Welsh club, who looked defensively strong but lacking in firepower, before leaving ahead of the final whistle.
But Sousa believes the Swans' final-day heartache could have been avoided as they finished the season with three wins in their final 13 games.
That poor finish included a seven-match winless run in March which Sousa last month claimed would not have happened had the club strengthened.
But despite missing out on the play-off which Sousa said was worth £60m, he says had achieved his goal of a top-10 finish set at the start of the season.
"The [Doncaster] game is the reflection of the season," he added after the Swans were beaten to a play-off place by a point to Blackpool.
Sousa fumes at '£60m' calls
"We dominated, created chances to score, lack of goals and the wrong decisions against us.
"It costs a lot for the club and the city. I read something two or three years ago from an English manager who said it cost them £60m and £60m for a club and for a city means a lot."
Sousa also said he will sit down with his players to discuss their futures with star midfielder Leon Britton out of contract, and fellow midfielder Darren Pratley and defender Ashley Williams among a few being touted for moves to the Premier League.
"I hope next week we can go through those things," said the two-time Champions League winner.
"I made practically all of the decisions for a while, but I cannot go through these before sitting with the board and to talk about what we can get for next season.
"We need to make the better decisions which is to be better than this season."
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