Finding themselves in a congested LaLiga mid-table, Betis entered this clash just six points adrift of the top five, but only seven points above the relegation zone.
The opening 20 minutes were quiet in terms of goalmouth action, albeit full of intensity, but Igor Zubeldia’s red card for pulling down Jesus Rodriguez as the last man turned the game on its head.
With the numerical superiority, Betis were eager to profit, and they had the perfect opportunity to do so around the hour mark when they were awarded a penalty after Antony was dragged to the ground by Aihen Munoz.
However, from 12 yards, Giovanni Lo Celso was denied by Alex Remiro as he missed his first spot-kick in six years.
There were further opportunities for Betis, with the electric Rodriguez hitting the post after Remiro saved from Isco, although Luka Sucic’s fierce drive from outside the area that crashed back off the crossbar was a reminder that the visitors could still be dangerous.
Nevertheless, Betis really began to put their opponents under pressure after the restart, and by the midway point of the second period, they were two to the good.
The first was a fantastic strike from Antony, who looks rejuvenated since his loan move from Manchester United as he scored his third goal in four matches.
The second was more fortuitous, as Rodriguez’s shot - following some impressive wing play - was deflected into the path of the onrushing Marc Roca, who hammered home from close range.
Substitute Roca, had previously scored just five times in 142 LaLiga matches, but he was soon on the scoresheet again, driving into the bottom corner from the edge of the area.
On what was quickly becoming a nightmare evening for Sociedad, things went from bad to worse when they were reduced to nine men following Sheraldo Becker’s late, high challenge on Angel Ortiz.
As such, the final few minutes were ultimately a procession, as Sociedad appeared content to limit the damage and Betis circulated the ball with ease.
All in all, this was a very good day at the office for the Verdiblancos, who end a run of five games with this home win.
Sociedad, meanwhile, have now won just one of their past five LaLiga matches, and with them having dropped off the pace for a top-six spot, they may look to prioritise the Copa Del Rey and UEFA Europa League instead.