Barnsley have been the surprise package of the whole Championship season and they're really serving it up to the big guns of the league under Valerien Ismael.

The Tykes survived relegation by the skin of their teeth last season thanks to a final day victory over Brentford and Wigan's collapse into administration combined, but the real progression of their team didn't become apparent until Ismael replaced Gerhard Struber earlier this season.

The Austrian headed across the Atlantic Ocean to the MLS and in came a former Bundesliga winner as a player in Ismael, who has not only improved Barnsley but made them promotion contenders.

A big factor into the improvement is the club's transfer model, where you will really only see them purchase players in their mid-20's or below for transfer fees.

As seen with recent sales like Ethan Pinnock, Kieffer Moore and Jacob Brown, Barnsley are happy to make profit on their players and re-invest, and there's certainly been some successful signings that still remain at the club.

Let's look at the 10 current Tykes with the biggest market value increase since their debut for the club according to transfermarkt.

Brittain was a recent summer addition from Milton Keynes Dons, with transfermarkt having his value down as £360,000 before he made the move to Oakwell.

The 23-year-old slotted straight into the right-wing-back role ahead of fellow youngster Jordan Williams, and has played 36 times for the Tykes this season and you'll regularly see him galloping down the right side of the pitch with the ball, just like Ismael likes his wing-backs to do.

Brittain has yet to break his scoring duck but has assisted five goals, with his transfermarkt value rising by £540,000 to a figure of £900,000 since he made his first appearance for the Yorkshire club.

Collins' rise in value is the exact same as Brittain's - £540,000 - even though for the first half of the season he could not get a look in from Ismael.

The Frenchman favoured Jack Walton in-between the sticks until the January 27 clash with Cardiff City at Oakwell, and since then 24-year-old Collins hasn't looked back.

The ex-Chelsea stopper has started every match since and that run of games - which has seen Barnsley lose just twice - may be the main reason why his value has gone from an undetermined number before he signed to £540,000 as his stats show that he's conceded less than a goal a game in the Championship this season (transfermarkt).

Barnsley bolstered their striking options in January not only with Daryl Dike, who has been getting all the headlines recently, but with Morris who spent the first half of the season on loan at MK Dons in League One.

A record of three goals in 18 third tier games wasn't the most prolific, but the Tykes saw something in Morris to bring him to Oakwell and he's so far delivered - scoring six times in 19 outings.

Morris' market value was just £135,000 when he signed - those six goals though have already made it rise to £720,000 and it may not stop growing if he continues to net between now and the end of the season.

Chaplin arrived at Oakwell in 2019 with a market value of just £180,000 - a figure that is definitely a lot less than he left Coventry City for at the time - but after his first season with the Tykes that number just had to go up.

The striker netted 11 times in his debut campaign for Barnsley but the current season hasn't been as kind to him - Chaplin has made 32 appearances but rarely lasts 90 minutes and has scored just three goals in the Championship.

Regardless of that though his market value stands at £900,000 - a £720,000 jump since his debut two years ago and there's still potential for that to grow.

This is one who you'd expect would be perhaps higher up the list after his performances this season, but understandably Styles' market value was quite small at £225,000 when he swapped Bury for Barnsley in 2018.

Styles had just 26 EFL appearances to his name at the time and it's only really this season where he's made his real breakthrough for the Tykes - in a left-wing-back position unfamiliar to him until he was placed there by Struber late last season.

The 21-year-old has simply flourished, scoring four times this season and assisting a further three goals to attract attention from some Premier League clubs - his current transfermarkt value of £1.44 million is a rise of £1.22 million and probably does him a disservice considering he could be sold for probably five times that figure.

Because of Woodrow having Championship experience before his move to Barnsley in late 2018, his market value was already at £675,000 when he was still contracted to Fulham.

That would only increase though the more times he played for Barnsley - he finished his first season with the Tykes with 16 goals as they were promoted into the Championship and he's continued to flourish, netting 14 times in the 2019/20 campaign and right now he's on 11 for the current season.

Understandably there's been growth in his market value since - it now currently stands at £2.25 million which is almost a £1.6 million increase - although like Styles, Woodrow could probably command a fee bigger than that.

Helik has been one of the surprise packages this season for Barnsley - little was known about him when he joined in September from Cracovia but he's probably been one of the main reasons for the club's success.

The 25-year-old has been a colossus and he's also a threat at the other end of the pitch too, scoring five goals which have helped Barnsley climb into the play-off spots.

His performances have led to a senior Poland debut this year and his market value of £540,000 when he debuted for the club now looks silly - it's increased to £2.25 million but that is a figure that Barnsley would probably laugh at for hours if a club came in with a bid for Helik tomorrow.

Dike isn't Barnsley's player on a permanent basis - not yet anyway - but his current market value of £4.5 million makes him the most expensive player in the squad.

The 20-year-old striker was already gaining a bit of a reputation in the MLS after his debut season saw him score eight goals for Orlando City, but that rep has only exploded since he made the mid-season loan switch to the Tykes.

Eight Championship goals later and now many Premier League clubs are tracking Dike, who debuted for Barnsley with a market value of £2.7 million so represents an increase of £1.8 million since that first game.

His current market value though is a snippet of what he will actually go for this summer you'd assume...

Andersen was a £900,000 capture from Danish side Horsens in the summer of 2019, with transfermarkt assessing his actual market value as £315,000 before he joined the Yorkshire club.

It's not always been good times for Andersen at Oakwell, but this season he's really come into his own and a partnership with Michal Helik will have only helped his development.

The 23-year-old has been an ever-present for the club this season, playing in all 41 games so far and his performances have seen his market value increase to £2.7 million - last season some Barnsley fans would have probably snapped your hand off to take that kind of money for him.

He's still yet to pen a new contract to commit himself to the Tykes beyond the end of this season, but since his arrival in 2017, Mowatt's market value growth has been the biggest by far.

A fee of £600,000 took Mowatt to Barnsley from Leeds United in 2017, with transfermarkt valuing him higher than that at £900,000 before he made his Tykes debut.

Mowatt didn't have a great start to his career at Oakwell as he was sent out on loan to Oxford, but since 2018 he's been such an important figure in the engine room, scoring 19 goals since then and has been the player that the team turn to when they need getting out of trouble.

His current market value of £3.6 million represents a £2.7 million rise and if he was under contract for next season, then bids in that region would surely come in for the midfielder.