Barnsley had yet to concede under Ismael but fell behind after just four minutes through Junior Hoilett, and they were comfortably outplayed as the match went on.
Harry Wilson earned a penalty, which Joe Ralls dispatched, before adding a third with a stunning strike to round off an emphatic and much-needed success.
Story of the match
Cardiff manager Neil Harris made big changes to his team after a very disappointing defeat at Queens Park Rangers three days earlier that had extended their winless run to four matches. There was a switch in formation to 4-4-2 and three changes of personnel, and one of the new men needed only four minutes to make an impact.
Hoilett might have had a chance at goal when goalkeeper Jack Walton came out rashly but showed enough determination to clear the ball out. However, straight from the throw, Joe Bennett was given time to measure a cross into the box which defender Michal Helik missed, allowing Hoilett to turn his body and fire the ball into the bottom corner.
Barnsley had enjoyed consecutive wins over QPR and Watford in Ismael's first week in charge, but they were struggling to make any kind of impact in this game and were placed under further pressure, with their former striker Kieffer Moore almost glancing in a header.
Walton had to make saves from a Curtis Nelson header and then Robert Glatzel’s prod towards goal, and Barnsley were still yet to register a single shot when Ismael took action in the 40th minute by replacing Elliot Simoes with Clarke Odour.
It almost immediately had an impact as they finally tested Alex Smithies, with Conor Chaplin denied after some fine control from a long pass and Patrick Schmidt’s follow-up blocked by Sean Morrison.
But Cardiff, who had seen Moore denied by another Walton save, took a decisive lead into the break, with a helping hand again from Helik. Another returnee to the line-up, Harry Wilson, played a one-two to get in behind and was felled by the Pole’s sliding challenge, allowing to Ralls to calmly dispatch a penalty into the right corner.
That left the Reds with a mountain to climb in the second half, and though a more pragmatic style of play after the break saw them hold more possession and gain some control over the game, they struggled to translate that into any real chances with Cardiff’s defensive ranks proving resolute.
A tedious second half was lit up only by Wilson’s brilliant goal to secure the three points for the hosts. The Liverpool loanee received a side pass from Ralls outside the box, took one touch to set the ball in front of him, and produced a delicious strike into the far corner of the net.
Moore was denied by the goalkeeper once more in stoppage-time as Cardiff had chances to make the result even more impressive, but they had done more than enough.
Harris makes effective changes
There were changes both in personnel and in system from Harris, with the usual 4-2-3-1 ditched for a 4-4-2, and it was a formation that worked a treat.
Cardiff are never afraid to hit long but having two players up front to aim for, with Moore joined up top by Glatzel, gave them an added threat that asked more questions of the Barnsley defence.
The other two changes saw Hoilett and Wilson introduced, and both had big impacts on the game and on all three of the goals. Despite playing as more traditional wingers than usual, both were advanced enough to provide an effective link for the strikers, taking their knock downs as well providing good service from the wings, while still adding a threat with runs into the box.
Having got the job done in a devastatingly effective first 45 minutes, the second half was, frankly, achingly dull, Wilson’s strike aside, but that would have suited Harris just fine as they never looked under even the remotest threat.
That was because the formation worked just as well, if not even better, off the ball than on it, with the two banks of four giving Barnsley no space to play in.
Direct game hits buffers
Ismael has puzzles to solve for the first time as Barnsley head coach as his honeymoon period was brought to an end with this bitterly disappointing performance.
After two matches in which their pressing was able to set the tempo for their direct passing game, they came up against a side whose style provided something of a kryptonite.
Cardiff’s willingness to go long made their pressing largely futile, and meant that they had to keep more players back than in their previous matches. When they did get the ball back, they found Cardiff’s two organised banks four nigh on impossible to swiftly pass their way through.
It’s a high-risk strategy that the Reds now aim for, and when it doesn’t work, it really doesn’t work. Ismael did show his willingness to change things though, with his side playing more pragmatically in the second half with more patient play and longer spells of possession.
It was a recognition that against certain teams and certain styles, they will need to adapt how they play. Other teams will take note of Cardiff’s success, and Ismael will need to find the answers.
Man of the match: Harry Wilson (Cardiff)
Wilson made a big impact on his return from injury, providing a dangerous threat from the right wing and producing two of the game’s big moments by winning the penalty and then scoring a spectacular third.