For a rookie umpire, the high spot is Walla Walla

Unlike plastic flowers that suddenly appear in a window box, major league umpires do not spring out of nowhere to become instant craftsmen in a demanding profession.

Instead they go through a lengthy learning process in the minor leagues, during which they are underpaid, overworked, and rarely appreciated by those they seek to serve.

Some quit en route to the top, because the job is just too tough mentally, physically, and financially. Some get fired, because they don't have the skills or the disposition. Others, still in the mainstream of their learning process, keep asking themselves: ''Is this what I really want to do?''

This story will introduce you to one of the latter - Bob Williams, a 22 -year-old physical education major at Cal Poly University in Pomona, Calif., who was a rookie umpire last year in the Northwest League. It is a six-team league operating in Oregon and Washington. It is limited to the use of rookie and second-year players and a place where aspiring young managers often go to prove themselves.

Williams got his appointment to the Northwest League from the people who run organized baseball after finishing near the top of his class at the school run by former American League umpire Bill Kinnamon in San Bernardino, Calif.

Among Bob's teachers during the five weeks he spent with Kinnamon were current major league umpires John McSherry and Nick Bremigan. Since Bob lived close enough to the school to commute, he was able to hold his tuition costs to

Each Northwest League team plays a 70-game schedule. Its season starts on June 24 and runs through Sept. 4. Two umpires are assigned to each game, with 90 percent of the league's schedule played at night and at ballparks that are almost always part of local sports complexes.

Williams's season-long partner was Ron Brown, who would be coming back for his second year in the league. In 1981 they drove several thousand miles together, shared the same hotel room to save money, and alternated calling balls and strikes as opposed to working the bases.

For this, each was paid $300 a month, plus $700 expenses, plus an additional 18 cents a mile only to Bob, who provided transportation. Williams managed to break even by using a diesel car that got 50 miles to the gallon and by frequenting several restaurants in league cities that offered free meals to Northwest League umpires on certain days.

If that financial arrangement wouldn't have prompted Bernard Baruch to slash his charts and graphs, consider that the drive from Medford, Ore., to Bellingham , Wash., took 11 hours. There was also the chance that if the restrooms were opened to the public too early, umpires were asked to dress while hiding behind a typewriter in some drafty press box.

But there were always things to break the monotony, like umpiring before a record crowd of 1,800 at Walla Walla, Wash., on the Fourth of July and then counting only 125 people in the same ballpark the next day!

''I think the main reason my partner and I worked so well together was that we both had the same goal before the season started - to be the best two-man crew in that league,'' Williams explained. ''I mean, this was serious business with us and we really worked to make it a smooth operation, learned the rule book, and never hurried our calls, which can often lead to mistakes.

''I was told one time by Doug Harvey (former major league ump) that players and umpires tend to get into competition with each other in the low minors and that was something I would have to watch,'' Bob added. ''Now that I've been in a league like that myself, I would have to agree.

''I think it happens because everybody is young, because everybody is trying so hard to get ahead, and because everybody wants people to notice that he's doing a good job. But to me umpires work best when they keep a low profile and just do their jobs and let the players do theirs.''

Asked where the most friction develops between umpires and gung-ho minor league managers, he replied:

''What a lot of rookie managers don't seem to understand is that they are not supposed to argue balls and strikes. These are judgment calls and belong to the umpire. Even though you might not want to, if a manager persists in coming out on the field and questioning your judgment, then you have to run him.

''I also had some problems with young catchers who thought it was smart to pull balls that were outside back into the strike zone and then look at you when they didn't get the call they wanted,'' Bob continued. ''Most of them didn't seem to understand that by doing this they were showing up the umpire in front of the crowd and causing problems. So you have to educate them to cut it out or you end up buying yourself a lot of abuse from the stands.''

Where does Williams go from here?

''Soon I'll probably be getting a new contract through the mail from the supervisor of professional umpires in the Western United States,'' Bob said. ''I hope it will be for a higher league and for more money. But if it's the Northwest League again, I'll probably sign anyway.''

''If I am moved up regularly and don't lose interest in umpiring because of the travel and being away from loved ones so much, then the majors will become a goal for me,'' he continued. ''Otherwise I would like to get involved in athletic administration at the high school or college level.''