Their departure has left a vacuum to be filled in the leadership department at Oakwell, even accounting for the fact that other leaders will naturally emerge over time.
It is why – allied to the addition of another physical, direct and pacy forward option following Daryl Dike’s return to the US – that the capture of another central midfield option and a senior defender are likely to be viewed as transfer priorities.
The club’s big forward target is towering Standard Liege frontman Obbi Oulare, with the 25-year-old having previous experience in England following a short spell with Watford.
Another option to help fill the midfield breach vacated by Mowatt will also be high on the wish-list alongside some senior defensive cover following the exit of another much admired unifying figure in Sollbauer.
It is something that new head coach Markus Schopp will be acutely aware of.
On the recruitment priorities for Barnsley, who have brought in just one player so far this summer in Devante Cole, with Luke Thomas and Patrick Schmidt having left on loan to add to the permanent exits of Mowatt and Sollbauer, Schopp said: “We’ve already talked about the older guys who left, especially in the midfield. We’re going to look for something, this is clear.
“Probably attacking (wise), we are looking for something different. We have to figure out which guys will fit best, not just anybody who will join us.
“There is a lot of stuff going on right now because we lost a couple of experienced guys. We have a lot of really young guys with a lot of potential.
“There are so many names running around right now, it’s up to us to find the right guys for the way we want to play. There are a couple of guys who have the quality to give us a lot, but there’s still a lot to speak about, so I don’t want to give too many details.
“I’m always in discussion with Paul (Conway). There’s a lot of discussions right now because it’s all about getting to know each player and Paul has some ideas so it’s all about figuring out in which direction we want to go.
“We have an identity of how we want to play and for that we need the right players.
“We have so many interesting English players too, so it’s all about finding the right mix. It’s not about old, it’s not about young, it’s about quality.”
Schopp has yet to make a decision regarding the complete make-up of his backroom team, having understandably prioritised working with his squad and preparing them for the rigours of a long Championship season in the early weeks of his tenure.
Fellow overseas assistants Joseph Laumann and Tonda Eckert remain at the club, alongside goalkeeping coach Kevin Pilkington.
Their input – and that of other staff members – is likely to be drawn upon by Schopp in his first foray in English football as he seeks to establish successful working relationships in the build-up to the new season.
He added: “Everything happened very fast, so it was so important to get here and get in touch with all the staff members. I have to get to know them better.
“It’s still a process where we have to figure out how (if) somebody will join us, but right now I can’t answer.”
On the importance of broadening his knowledge of the Championship in double-quick time by way of liaising with existing staff members, Schopp continued: “We are talking a lot about this because a couple of guys on the staff got to know the Championship well last season.
“I’ve always seen how many games we have to play and this is a tough Championship.
“We did it well last season, but I think we have to do it better next season. I and my staff are trying to figure out how it works best for the team.