It’s been a bad year for Randy Johnson. Going into yesterday’s game against the Detroit Tigers, the future Hall of Famer had pitched 26 1/3 innings in May, in which he’d given up 27 runs and seven home runs. He’d pitched poorly twice against Boston and once against the Mets, proved unable to hold the fort when spotted a big lead, and opened himself to speculation that he was, simply, done.

As Johnson said after the game, “One good game doesn’t make a whole year,” and that’s true even when the one game is a sterling six innings of shutout baseball against the team with the best record in the sport. It’s a sign of how steep the fall Johnson has taken that manager Joe Torre took him out of the game after he allowed the leadoff man to reach base in the seventh inning, despite his having not even neared 100 pitches. Randy Johnson has won five Cy Young awards, and it’s surely been a long time since anyone felt constrained to make sure he left a big game on a high note.

Still, a great game is a great game, and yesterday offered some hints that Johnson might find a way to be effective with vastly diminished stuff. Many theories have been offered to explain his struggles – a crisis of confidence, a poor relationship with catcher Jorge Posada, the sudden arrival of baseball mortality – but Johnson’s problems are quite common. Old pitchers, and especially 42-year-old pitchers, are not supposed to be able to throw the ball in the high 90s, precisely where they want it, at all times. Johnson was able to do that for many, many years; that’s why he’s going to the Hall of Fame. The question now is whether he’ll be able to get by without doing that. I think he will.

In recent games, Johnson has fallen into the usual pattern of a pitcher whose approach is based on having better stuff than he has. He’s pounded the strike zone with fastballs and flat sliders.When these pitches don’t have enough on them, they turn into line drives and home runs; when they do have something on them, they end up out of the strike zone, and hitters just wait for the juicy pitch they know is coming.

Johnson, because of his various back and knee problems, can’t really afford to take enough off his pitches to allow himself to spot them with real precision, because he can’t repeat his delivery precisely enough to ensure that command is always going to be there, and he can’t throw quite hard enough to make up for the lack of command.It’s a quandary.

The adjustment he has to make – and it’s certainly a heck of a lot easier for me to write about than it is for him to do – is to focus on pounding the ball inside, which has all sorts of advantages. Beside just making hitters uncomfortable,it makes your outside pitches more credible, it keeps hitters from getting full extension, and it keeps them from shooting the ball into the gap the other way. Basically, it makes them work for what they get.

When veteran pitchers talk about establishing the inside part of the plate, they’re not (only) indulging in macho bluster; they’re speaking about a central reality of the game, which is that if you don’t have the stuff and control to just toss the ball over the heart of the plate and watch hitters wave at it, you have to own the inside. Tom Glavine, having mastered this idea, is on the best run of his illustrious career at 40, and there’s no reason Johnson – who still has more vicious stuff than all but a handful of lefty starters – can’t similarly reinvent himself.

What was encouraging about yesterday’s start wasn’t so much the results as how Johnson got them. Of four basic sorts of pitches – inside strikes, outside strikes, inside balls, and outside balls – he threw the first sort about 40% of the time, and each of the rest 20% of the time. This approach didn’t result in a lot of strikeouts, but it did result in a lot of bad contact of off-balance hitters who weren’t quite sure what to look for.

This sort of mixing-and-matching hasn’t always been necessary for Johnson, but if he can throw strikes inside twice as often as he throws any other sort of pitch and make sure that if he misses with his slider he does so near the shoetops rather than the kneecaps, he’ll be very effective from here on out.

Can Johnson consistently attack hitters this way? To ask the question does him a disservice. His velocity, command, and delivery in his prime made him a terrifying pitcher, but no one pitches the way he did without developing game plans and being able to execute them. The idea that he’s not mentally tough enough to succeed without his best stuff is preposterous; though he alone can really know, the question is really more one of ego. If Johnson is willing to let the game plan assume greater proportional importance than his athletic skill, he’ll revert to form given his health; if not, he’ll write a disappointing end to his career.

There’s no way to know what will happen, but if Johnson can do what he did yesterday, there is a way to know what can happen. Randy Johnson is a long way from done.

tmarchman@nysun.com