Reliever Neil Allen was due back in Mets uniform last night. The "arrangement" the club made was a visit to a New York treatment center, after which Frank Cashen, Mets executive, reported this evaluation: while "Neil had unfortunately and unwisely over the past few weeks used alcohol to excess because of overstress," he could return to work immediately and fall back on counseling to cope.

Allen had said that after a bad game in Cincinnati last week he downed a bottle of vodka in his hotel room. Craig Swan said he did that once in 1981 and "I'm no alcoholic" . . .

Tom Seaver said Allen is "using it (claim of drinking problem) as a crutch because he won't face up to the real problem. He's having a rough time (0-3, 9.32 ERA) . . ."

In San Diego, Manager Dick Williams and General Manager Jack McKeon get extensions (Williams two years, McKeon one) through 1986. This just after Padres President Ballard Smith endorsed their decision to cashier left-hander Chris Welsh for defying Williams' orders on pickoff throws in the fourth inning of Welsh's start Saturday night at Pittsburgh.

"If you don't like the way I'm doing it, get someone else out here," Welsh said when the pitching coach, Norm Sherry, came to the mound. Williams did get someone else out there, and said afterward Welsh "will never pitch again as long as I am the manager." Welsh explained his (last?) stand to reporters later: "When a pitcher is on the mound, he is king of the hill."