
Those 16 players include those who were released, or came to the end of loan deals at the Riverside - but not those who were loaned out by Boro this season, whose fortunes we previously looked closer at.
From league titles to Boro-related drama, this is a look at what happened next for the players who left Boro in the last 12 months.
After a successful loan spell at Boro in the second half of last season, Boro’s enquiries to sign Travers permanently were knocked back, as the keeper’s representatives indicated his lack of interest in a return.
Instead, Travers interestingly opted to join Everton, who had long-established England number one Jordan Pickford in their ranks. A lucrative deal, no doubt, but the result was Travers playing only two Carabao Cup games last season.
After agreeing to the early termination of his deal at the Riverside, the Aussie keeper eventually signed a deal at Japanese second-tier side RB Omiya.
It was an interesting first year because the Japanese league campaign didn’t run due to their transition to a summer-to-spring league format, which will kick-off in August.
Instead, a one-off tournament was held during which Glover established himself as first-choice, making 17 appearances. Omiya would finish 15th overall and are now set to appoint former Stoke City boss Narcis Pelach as head coach.
As Boro decided to put their faith in Sol Brynn, Hemming made the decision that, after numerous loan spells, the time was right to seek a new permanent home. Despite his two loan successes at St Mirren, it was League Two side Chesterfield he joined.
There, the goalkeeper was first-choice for much of the season and was described by his coach as the ‘best keeper in League Two’ in January. But he lost form and therefore his place in the team towards the end of the season.
He was benched for the final eight league games, and the losing play-off semi-final games against Notts County. Despite that, he was still voted the Player of the Year.
The young Dutch center-back ended his two-year stay at Boro to switch to Bundesliga side FC Koln last summer. It was a slow start for the classy defender, however, as an injury ruled him out for over two months after just two games.
He initially regained his place quickly and made 14 appearances in total. But he was an unused sub for the last six games of the season, as he lost his place in the team. Koln finished 14th, avoiding a relegation play-off (for finishing third bottom) by just three points.
Released at the end of last season, Dijksteel made a move to Turkey last summer, joining newly-promoted Kocaelispor in the Turkish Super Lig.
They were one of the favourites to be relegated therefore, but shocked many in finishing tenth in their first season in the top flight. Dijksteel was a top performer for his new side, making 36 appearances in total.
Reflecting on the campaign on Instagram, the Boro favourite wrote: “My first season in Turkey was a wonderful experience. On the pitch, we achieved our objective, shared unforgettable victories and experienced special moments.”
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After a superb first loan spell at Boro, the old saying, ‘never go back’ rang true for Giles, whose struggles in the years since continued in his second spell at the Riverside.
Returning to Hull last summer, he fortunes completely changed this season under new boss Sergej Jakirovic. He re-established himself in the Hull City side, registering eight assists across 37 appearances - the lost of which was beating Boro in the play-off final at Wembley.
After his loan spell at Cincinnati ended in December, the expectation was that Engel would re-join the Ohio side permanently. Instead, they opted against a move and he moved to Real Salt Lake instead.
The Dane has since been a regular, starting all eight of the MLS games he’s been fit for. His side currently sit third at the halfway stage of the Western Conference, with the campaign taking a break until July for the World Cup.
Howson’s long association with Boro came to an end last season, with the veteran midfielder looking to the next stage of his career in taking a player-coach role in Leeds United’s U21 squad. He made 16 appearances in total.
He told the club website in March: “The lads have been brilliant. I must say, irrespective of different levels of ability, it is great to work with them because their attitude and application has made my transition of stopping playing first-team football so much easier.”
After struggling for game-time at Boro in the first half of this season, he returned to Manchester City in January. Premier league squad roles meant the Norwegian was never going to be able to make a league appearance.
But City decided he'd be better-suited back there, where he’s regularly been pictured in first-team training alongside their stars like fellow countryman Erling Haaland.
Those squad rules didn’t stop the 19-year-old being involved for Pep Guardiola’s side in the Carabao Cup, and he was an unused sub in their semi-final second-leg win over Newcastle United, but didn’t make the squad for the final.
Boro’s big loan star of last season, injury ended his campaign prematurely before he made a move last summer from Liverpool to Bournemouth.
The Scotland winger was hit by another early injury blow which kept him out for four months. He made only nine appearances for the Cherries last season, but has made the Scotland squad for the World Cup.
The former Juventus winger struggled to make much of an impact on Teesside. Instead, he spent the first half of this season on loan at Championship strugglers West Brom, where he made 24 appearances.
That move was cut short, however, and he joined Serie A side Pisa for the second half of the campaign. There, he made only five appearances, only one of which was a start and resulted in him being axed at half-time.
After a successful loan spell at Darlington, academy graduate Lennon made a permanent switch to Barnsley in January. The winger, 20, only managed three sub appearances in the second half of the League One season, however. He did manage to score one goal.
After leaving Boro for Southampton for what he felt was a better chance at promotion to the Premier League, Azaz scored 12 goals, including one at Wembley in the FA Cup semi-final, and registered nine assists.
But his promotion dreams blew up in smoke when Southampton and boss Tonda Eckert admitted cheating on three separate occasions by spying on opposition training - something which blew wide open after being caught by Boro ahead of the play-off semi final.
They were expelled from the play-offs and will start next season on minus-four points, while an FA investigation is ongoing and could see Eckert banned.
After opting to leave Boro for guaranteed game-time, Coburn had another campaign that was impacted by injury. But he returned strongly in the second half of the season, scoring ten goals in total, including two against Boro to secure a third-placed finish. They then lost in the play-off semi-finals to Hull City.
After a disastrous loan spell at the Riverside, Iheanacho left Sevilla on a free transfer and joined Celtic just before his former Leicester City boss Brendan Rodgers resigned.
After a successful loan spell, Boro allowed Finch to join South Shields on a permanent basis as they chased promotion from National League North.
The forward got seven goals for the Mariners, but they finished second in the table and ended up missing out on promotion after losing the play-off final to Kidderminster Harriers, who featured Boro loanee Brayden Johnson.
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Middlesbrough are preparing for a big summer as they look to rebuild from the heartarche of missing out on promotion to the Premier League.
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