You have to love this game. Two weeks ago, I wrote a column that all but buried the Yankees, who were 11-17 and coming off a pair of embarrassing losses to the Devil Rays. They’d let the Fish bite them one more time in Tampa Bay, then drop the an extra-inning game to the A’s in the Bronx to fall to 11-19 the first time the Yankees had been under .400 at the 30-game mark since 1966.

They haven’t lost since. A ten-game winning streak–entirely against the A’s and Mariners–has pushed the Yankees above .500 and, at least for now, rekindled the idea that this Yankee team is a club on par with the Red Sox in the AL East.

I’m not buying it. I think we learned a lot more about the A’s and Mariners over the past two weeks (especially the A’s, an issue I’ll need to address in the near future). The Yankees have played better baseball, at least on the surface, but the key to this surge is the poor competition they’ve faced. The A’s can’t hit, and they made Yankee starters look very good, scoring just nine runs off them in five losses. The Mariners can’t pitch, and have allowed 36 runs to the Yankees in five losses.

The streak is no fluke; the Yanks have outscored the AL West teams 77-33 in the 10 games. The starters have generally been able to keep scores down and go deep into the games. When they haven’t, Derek Jeter and friends have put up a couple of touchdowns. It’s a nice system, which just proves the old adage: when half your lineup is putting up an 1100 OPS, it really doesn’t matter what your problems are.

(Hey, it was an old adage in my neighborhood.)

The biggest Yankee story has been the hot streak of Tino Martinez, who blasted homers in each of the first five games of the streak, and has eight in the ten wins. While Jason Giambi hasn’t put up much of a fight, it’s Martinez’s performance–and his popularity–that has changed the guard at first base for the Yankees. This has the potential to be a disaster; Martinez is now entrenched at first, and as good as story as he’s been, he hasn’t been a real asset since 1998. It’s much more likely that he reverts to .260/.350/.440–inadequate for a first baseman–than it is likely he’ll continue to impersonate Carlos Delgado. Three doubles to go with those dozen homers are a warning sign.

Whether by emotion, demotion or locomotion, the Yankees have to get Giambi going. With both Tony Womack and Robinson Cano in the lineup, the Yankees can’t afford to just dismiss a player who, when he was right, was an OBP machine. Giambi’s problems making contact are destroying his performance; if he can straighten them out, he still is a dangerous power hitter and a source of OBP. Releasing him and his monstrous contract isn’t a viable option; working to get value from him is.

It’s hard to evaluate the pitching staff off the last ten games. As excited as people are about Mike Mussina‘s good work and the signs of life from Kevin Brown, it was the A’s and Mariners. The A’s are a horrible offensive team, and the Mariners better, but still below average.Carl Pavano‘s game last night was a reminder of how much he misses the wide open spaces of Dolphins Stadium.

While the last 10 days are a good example of what $200 million will buy you, the Yankees still have all the problems they had when they were 11-19. The infield defense is better for the addition of Cano, and that’s about it. The outfield defense is worse with Womack, the lineup will end up losing ground if Cano–whose batting average is higher than his OBP, courtesy zero walks in his first 46 plate appearances–remains the starter at second base, and there’s still the incongruity that is Womack in the outfield with Bernie Williams as part of a pink elephant platoon at DH with Giambi. That’s without even getting into the lineup that has Womack batting second, Alex Rodriguez in the #5 slot, and Williams occasionally as low as ninth.

The Yankee defense has improved over the past two weeks from “historically bad” to merely “worst in the game,” and the Reds are giving them a run for their money in that regard. You can credit some of the run prevention over the past couple of weeks, although it’s hard to separate that out from two pretty bad opponents and three parks that are bad for balls in play. How Womack and Hideki Matsui co-exist–whether they can avoid bringing back memories of the 1989 Dodgers’ “Tribute to Triples” outfield or any Pete Incaviglia-in-center-field video clips–is going to go a long way to wards determining whether this defense can be saved.

The Yankees were never going to be a .400 team. I was the most pessimistic of anyone about their chances and I saw them winning 87 games, enough to make them a wild-card contender. They ran into some soft competition at exactly the moment they needed, and they did what good teams have to do: beat up on the league’s weaker teams. It gets tougher now, as they play the Mets and Red Sox on successive weekends, and perhaps tougher still now that the expectations have been raised by the winning streak.