If Everton fans felt things could not get any worse after the 5-1 midweek capitulation at Goodison Park to mid-table Italian side Atalanta in the Europa League, the calamity at St Mary's dashed even those faint hopes.
With their chance of progression to the knockout stages in Europe already over, Unsworth fielded a second-string team on Thursday. Yet at Southampton, there could be no excuses with Everton at full strength.
Having fallen behind to Dusan Tadic's goal, Gylfi Sigurdsson's stunning strike levelled matters on the stroke of halftime, giving Everton the chance to ride the momentum after the break.
Instead, before the hour mark, the game was beyond Everton with Charlie Austin netting a pair of headers to put Southampton in command and Steven Davis capping a fine Saints' performance with a fourth late on.
It spelt more misery for Everton against a Southampton side who had scored just nine goals this season before Sunday's encounter amid their worst start to a Premier League campaign since 2012-13.
"There is a good spirit in training," Unsworth told reporters after the match. "But when we come to a game situation, it changes. We had a great training session yesterday, and everything we were looking for, we got."
Everton's ineptitude told a very different tale, though, and their lack of effort seemed to be epitomised, ironically, by the performance of a former Southampton stalwart Morgan Schneiderlin.
Already having had a seemingly fractious relationship with Unsworth after being dropped for walking out of a training session earlier this month, Schneiderlin made just 16 touches in the first half.
Though he improved marginally after the interval, he still only competed for five duels all match. His direct opponent, Pierre-Emile Hojbjerg, went in for almost double.
Everton have now shipped 28 goals already in the Premier League alone, the most any Toffees' side have conceded after 13 games since 1958-59. Since Unsworth took command, they have conceded 21 in seven games in all competitions.
Unsworth, a former Everton favourite as a player, is well liked by many media, and holds his club in high regard but Sunday's defeat had fans and pundits all asking again how long this punishment could go on?
Majority shareholder Farhad Moshiri said on Friday he was "very close" to naming Ronald Koeman's full-time successor. After such a torrid week, Unsworth cannot now be expecting a call.
(Reporting by Peter Hall; Editing by Ian Chadband)
