Sunderland have endured their fair share of transfer gaffes over the years as they have learned the hard way that not every new arrival ends up being a roaring success.

One manager who suffered a disaster with the Black Cats in the market was Dutch head coach Dick Advocaat as the manager brought in Adam Matthews during his first window in charge on Wearside.

The club snapped the full-back up for a fee in the region of £2m from Scottish giants Celtic in the summer of 2015 with Advocaat hailing the signing at the time, saying:

"Adam is a welcome addition to our squad. We know that we need quality players to improve competition for places in the side."

What happened to Adam Matthews?

He endured the worst possible start to his time at the Stadium of Light, though, as the defender suffered an ankle injury in August and was ruled out until October - missing nine competitive matches.

This led to the Welshman heading out on loan to Championship side Bristol City for the second half of the campaign, where he played nine times in the second tier, before heading back there for another loan spell in 2016/17.

Matthews featured in 12 matches for the Robins in the league that season, as Sunderland were relegated from the Premier League, and was then given an opportunity to feature for the Black Cats in 2017/18.

The right-back, who reporter Ross Gregory dubbed a "flop", ended up playing 34 times in the Championship as the team dropped down to League One. He averaged a Sofascore rating of 6.77 - placing him 13th in the squad - with that an indication the dud failed to be a standout player for the club in the second tier.

In 2018/19, Matthews played 23 matches in the third tier of English football - featuring in half of their games - and was then released by the club at the end of that campaign.

Then-Championship side Charlton picked him up on a free transfer that summer with the Wales international going on to play 89 times for the London club - who were relegated in his first season.

His spell with the Addicks ended in the summer of 2022 as the defender was snapped up by Cypriot outfit Omonia Nikosia, who the full-back has played 27 times for to date - including five appearances in the group stage of the Europa League.

On that evidence, it's clear to see Advocaat endured somewhat of a disaster with the signing of Matthews in 2015. The flop went on to struggle in the Championship and League One, despite being signed as a Premier League player, and was released for nothing after being bought for £2m.

At the age of 31, the defender is now plying his trade in Cyprus instead of competing at the top level in England and it is fair to say that his move to the Stadium of Light did not allow him to kick his career on.