Is the Yankees' half-billion dollar investment paying off?

NEW YORK -- Between the end of the 2013 season and the beginning of spring training 2014, the New York Yankees committed nearly a half-billion dollars to four players, with one goal in mind: to return to October baseball after missing the postseason for only the second time in 18 years.

So far, they have yet to recoup hardly a nickel -- or a playoff game -- on their investment.

Which doesn't necessarily mean these were bad deals, only that they have yet to reveal themselves for their true value. As Yankees GM Brian Cashman points out, "We never won a World Series with Mike Mussina, but I think he lived up to his [ultimately eight-year, $109 million] contract and performed at a high level and made us better. So in that respect, it was a good contract."

Mussina went 123-72 as a Yankee between 2001-2008, during which the club went to the World Series twice, losing to the Arizona Diamondbacks in seven games in 2001 and to the Florida Marlins in six in 2003.

And yet, history judges the Mussina deal as a success. How will history judge the signings of Jacoby Ellsbury, Masahiro Tanaka, Brian McCann and Carlos Beltran?

The quartet was signed in rapid succession after the Yankees decided to pass on giving Robinson Cano the 10-year deal he was demanding. Instead, Cano signed with the Seattle Mariners and Ellsbury, Tanaka, Beltran and McCann became Yankees.

But despite signing the four to long-term contracts totaling $438 million in guaranteed money, the Yankees missed the playoffs again in 2014. And as the 2015 season hurtles to its halfway point, the Yanks remain in a four-team dogfight in a diminished but still highly competitive AL East.

And of the four players signed before the 2014 season, only one -- McCann -- is performing anywhere near his career standards this season; the other three have either been slowed by injury or bedeviled by underperformance.

And while all four have a chance to rewrite the narrative, it is generally assumed that the early years of a long-term deal are when a player can be expected to perform at his best; the longer a contract goes on, the more a club is likely to experience diminished returns on its investment.

"Money doesn't always equate to performance," Cashman acknowledged. "In fact, most of the time it will never equate. That's the cost of doing business. Signing a player to a long-term contract is like buying a car. They don't tend to get better with age, and the ones that do are probably cheating."

Currently, Ellsbury is on the disabled list -- he has not played since May 19, when he sprained his right knee on a swing-and-miss -- and despite staying healthy for most of 2014, eh has missed more games this season (40) than he has played (37). He is in the second year of a seven-year, $153 million contract.

Beltran had a miserable 2014, batting just .233 with 15 home runs and 49 RBIs, all well below his career averages. He also missed 53 games with an elbow injury that required off-season surgery.

And while both his body and his bat have been healthier this season, he left Tuesday's loss to the Los Angeles Angels with a rib injury. He is batting .260 with seven home runs and 30 RBIs in 66 games so far. Even Beltran himself cautions that at 38, he no longer should be expected to be the player he had been for 16 seasons prior to arriving in the Bronx. His three-year, $45 million contract has one more season to run.

McCann started slowly in 2014 but rallied to put up mostly respectable numbers (.232-23-75, though with a career low .692 OPS), and in 2015 is on pace to match or come close to his career averages.

But it is Tanaka who is possibly the cause of the most consternation, coming to the Yankees with the reputation of being a lights-out starter in Japan, and carrying the baggage of a seven-year, $155 million contract, not counting the $20 million posting fee.

Tanaka was a certified ace in Japan, with a 99-35 record and 2.30 ERA in seven seasons with the Rakuten Golden Eagles. And in the first half of his first season as a Yankee, Tanaka seemed to be able to duplicate that success in the States.

Then came disaster, a partially-torn ulnar collateral ligament in his pitching elbow suffered on July 8 in Cleveland, and since then, Tanaka has not been the same pitcher.

Through 18 pre-injury big-league starts, Tanaka was 12-4 with a 2.51 ERA and was being talked of as not only a potential Rookie of the Year, but a Cy Young candidate as well. He had allowed just 111 hits in 129 1/3 innings, struck out 135 batters, walked just 19, and had a WHIP of 1.00, lower even than his WHIP in Japan.

But in his 11 starts since -- including two made last September after missing two months while the Yankees attempted to rehabilitate the injury without surgery -- Tanaka is 5-4 with a 4.33 ERA. He has allowed precisely a hit an inning, and combined with 13 walks, has a WHIP of 1.21.

And while Cashman says he has been more than satisfied with Tanaka, the pitcher gave ESPNNewYork.com this withering self-assessment: "I have to say that I'm not satisfied at all because of the fact, as you know, I've been on the DL last year and this year, as well. That said, I don't think I've done a very good job."

Tanaka's two most recent starts were particularly distressing: in back-to-back appearances, Tanaka allowed 11 earned runs in 10 innings, including six home runs. Last Saturday, Tanaka was staked to a 6-0 lead over the Houston Astros -- and subsequently gave it all back, including surrendering three home runs. The Yankees wound up winning the game, 9-6, but such a turn of events in a Tanaka start would have been unthinkable a year ago.

Still, Cashman said, "When he's been healthy he's been everything we hoped he could be. Outside of his last two, I really think he's been great."

After a slow start in April, in which he batted .162, Beltran has gradually heated up. In May he hit .298 with four home runs and in June hit .300 with three homers and an .866 OPS -- 20 points higher than his career average. But he has not played well in the field, and his defensive liabilities have threatened to reduce him to a bench player, especially with Alex Rodriguez performing above and beyond all expectations as the full-time DH.

"Last year was very disappointing because I came in with the expectation of helping the team," Beltran said. "Once I got hurt, I was never the same player. The first month [this season] was a bad month. But at the end of the day, you have to play the whole season before you can evaluate your season. Right now, I feel like physically I'm healthy. I'm looking forward to finishing the season strong and hopefully we are in the playoffs."

But Beltran added a note of caution: "I'm not 21 anymore. I'm 38. That doesn't mean I'm broke, but they won't see the Carlos who was stealing bases and making crazy catches in the outfield. Of course, every year passes by, you lose a little bit of everything. I still feel like I can be productive."

At 31, McCann should be in his physical prime, and after his adjustment period last season, appears to be settling in as the same type of offensive player he had been during his nine seasons with the Atlanta Braves. Where he has made a marked improvement is in his play behind the plate, particularly in throwing out baserunners.

As a Brave, McCann had caught an average of 24 percent of runners trying to steal; but in his first year as a Yankee that number jumped to 37 percent (29 of 78). So far this season it has improved even further, to 44 percent (12 of 27).

McCann credits his improvement behind the plate to working with Yankees bullpen coach Gary Tuck. As for his offense, he acknowledged that 2014 got off to a very bad start.

"Last year, I felt like I had some mechanical things off," he said. "I was getting 2-0, 90 mph fastballs that I knew were coming and I was fouling them off to the third base dugout. I'm having consistently better at-bats this year."

Ellsbury has probably been the biggest puzzle so far; when he is on the field he has been among the Yankees' most productive hitters. But he is a quintessential leadoff hitter whose game is based on his legs, similar toBrett Gardner. He is not a game-changer in the Mike Trout/Bryce Harper/Giancarlo Stanton mold, and his speed-based game can only be expected to diminish as he ages. Ellsbury will turn 32 in September and he will be approaching his 37th birthday in the final year of his contract. The Yankees also hold a team option for an eighth year (2021), in which Ellsbury will turn 38.

Despite the lack of immediate dividends from the marquee signings, Cashman had nothing but praise for the four players, although he did admit, "The timing of your story is beneficial to my answers, because they're all playing well right now."

He called Ellsbury "a stud" and "a difference-maker in our lineup." After acknowledging the poor starts of both McCann and Beltran, Cashman said both were performing above the league average at their positions.

Of McCann, Cashman said, "Last year was more the aberration, this year is the norm," and of Beltran, "Slowly but surely he's getting back to the player we're used to seeing."

He did admit, however, that Beltran's fielding deficiencies are something the Yankees will have to live with, and that Rodriguez's resurgence makes a move to DH for Beltran basically undoable right now.

"That's just the way it has to be," Cashman said.

On the whole, Cashman said the deals should be evaluated on a case-by-case basis. When asked if, given a second opportunity, he would make the same deals again, he said, "We made plays on every one of them for a reason. There is no going back."

Like everyone else, Cashman can only look to the future to determine whether the Yankees' big investment will turn out to be a huge success, or a monumental bust.