Steven Vonk, 51, from Westbury Street, Brynmill, denied murder but admitted manslaughter to the assault on 25 July, which was accepted by prosecutors on Monday at Swansea Crown Court.
Judge Paul Thomas KC told Vonk he had committed “unprovoked gratuitous thuggery”, and would serve half of his sentence in prison, and the rest on licence.
The court heard how Vonk, who had been drinking all day in The Mill, punched Mr Matthews after he apparently swore at him outside the pub.
William Hughes KC, prosecuting, told the court CCTV captured Mr Matthews raising a thumb at Vonk on the evening of 25 July. The victim was then punched without any reason, the barrister said.
“Mr Matthews immediately fell backwards and hit the ground,” he said.
“He was seemingly knocked out by the force of the blow.”
The court heard Vonk left Mr Matthews unresponsive on the ground and was arrested the following day.

Mr Matthews sustained a severe traumatic brain injury and continued to deteriorate in intensive care which led to doctors having to explain to his family that his injuries were unsurvivable. Life-maintaining therapies were withdrawn, and Mr Matthews died at lunchtime on July 27.
Serena Matthews, daughter of Timmy said in a written statement read to the court that her world had “changed forever.”
“I’m tormented at the thought of what my dad endured… and how alone and scared he must have felt.
“Dad was a loving character. Our family and everyone in the community is in shock.
“He was my best friend, and I will never get him back.”
In sentencing, Judge Thomas KC said:
“You violently ended the life of a 63-year-old man who had many years of life awaiting him.
“These courts see time after time after time that a single heavy punch can be, and very often, is fatal.”
With a one-third discount for his guilty plea, Vonk was sentenced to three years in prison. He will serve half the sentence in custody before being released on licence to serve the remainder in the community.
[Lead image South Wales Police]
