Darryl Sittler, Mr. Hockey to a lot of Toronto folks and a pain to cantankerous owner Harold Ballard, has become a Flyer--just in time to plug an unexpected, big gap in the center of Philadelphia's front line: Bobby Clarke out four weeks with a broken foot.

Sittler, former Maple Leaf captain claiming to be under such stress in Toronto the past 2 1/2 of his 11 1/2 years that he has been on leave the club's past eight games, won his demand to be traded either to Minnesota or Philadelphia. As Sittler exited Maple Leaf Gardens, UPI reports, "crowds of teen-agers milled at the doors, some crying, some shouting for Ballard to be traded."

In return for Sittler, 31, the Flyers yielded futures--then learned that Clarke's supposed bruise was a break; on top of knee problems for wings Tom Gorence and Paul Holmgren. Sittler reports today, like the Lone Ranger.

No. 1 NHL center Wayne Gretzky has agreed to Edmonton Oiler owner Peter Pocklington's promised new deal: reckon $20 million in a 21-year package; cash, real estate, etc. Leapfrog Gretzky over L.A.'s Marcel Dionne ($600,000) as salary champ--now.

Those other Spectrum tenants, the NBA 76ers, land help for decimated front court: Mike Bantom from the Indiana Pacers, for cash; homecoming for a St. Joe's alum . . . So desperate had the Sixers become with Darryl Dawkins' broken leg that owner Harold Katz spoke of about checking out Wilt Chamberlain, 45 . . . And big swap, San Diego sent its top scorer, guard Freeman Williams, to Atlanta for ex-UNC forward Al Wood, the Hawks' No. 1 draftee, and li'l Charlie Criss . . . Large NBA news, too, is Buck Williams, all-star!

When he could yet be leading Maryland to ACC glory, he is one of seven named by the Eastern Conference coaches to fill the roster of 12 for the All-Star Game Jan. 31 in the Meadowlands, N.J. Net Williams' home arena. Plus: Michael Ray Richardson, Dan Roundfield, Bobby Jones, Robert Parish, Bob Lanier, Sidney Moncrief . . .

Joe Sambito, the star Houston reliever, was confronted by the business end of a .32-caliber revolver brandished by his former buddy on the Astro pitching staff, Mark Lemongello, according to Florida detectives investigating the alleged kidnap/robbery of Lemongello's cousins Mike, former pro bowler, and Peter, ex-Vegas entertainer, by Lemongello and another pitcher, Manny Seoane (cups of coffee with Phils, Cubs).

Seoane surrendered Tuesday night, released on $10,000 bond; Lemongello still at large. Investigators said the incident climaxed a dispute between Lemongello, 26, and cousins over finder's fee for a home construction job the brothers were doing for Sambito in Feather Sound subdivision north of St. Petersburg. Police said Sambito and a landscaper were at the home site when the two suspects arrived and began fighting with the brothers. Sambito tried to intervene but the gun backed him away. Mark Lemongello and Seoane are accused of then abducting the brothers, holding Peter in a van while Mark forced Mike to withdraw more than $50,000 from a safety box, finally leaving them in a wooded area . . .

Progress reports: Reggie Jackson and Angels, meeting in Phoenix five hours, agree to meet further . . . Bob Irsay, after confab with Gov. Harry Hughes about Irsay's Colts and Memorial Stadium improvements contingent on long-term lease: "We're staying. We'll have a redone stadium very shortly."

Mike Ditka introduced in Chicago as NFL Bear coach on three-year contract; as for inherited assistants, "I can work with anyone."

Resigned: Joe Sullivan, as NFL Cardinal exec, for which he left Redskin staff in '73.

A. "Love" in tennis, on dit, comes from French l'oeuf: egg--as in goose egg . . .Q. The night Wilt the Stilt scored 100 points in the NBA: his team's second-high scorer ???