Look at Asia's best-performing currencies, and this dilemma, facing investors everywhere, is writ large.

The top five gainers against the dollar this year include high yielders, safe havens, global growth plays and rate-cut bets.

Amid that apparent confusion in themes one conclusion can be drawn:

This rally is about the dollar and the respite granted by still-easy monetary policy in the U.S., not real optimism.

The high yielding growth stories in there are the Malaysian ringgit and the Indonesia's rupiah.

Indonesia for one has a genuinely strong story of its own, with infrastructure spending and falling interest rates to support growth.

Singapore too is often a reflection of the regional and global outlook.

That might support the idea of a confident growth rally,

if it weren't for the fact that most economists are, if anything, moderating their forecasts for economic growth this year.

But it's the ringgit's outsized gains, up 10.9%, that really undermine the idea of a strong local growth driver.

Few economists are positive on its outlook and, rocked by the scandal surrounding the 1MDB state investment fund,

Kuala Lumpur's politics look increasingly troubled.

It appears to be the rebound in oil that's driven the rally in the ringgit.

Australia supports this too.

Its currency, up 4.9%, has been helped by the rebound in iron ore and other commodities.

But soggy retail data on Monday left alive rate-cut forecasts.

In other words, it isn't a growth story either.

The Japanese yen is perhaps the strongest indicator that this rally is driven by factors other than confidence.

It's 8% higher against the dollar this year, and remains stubbornly strong as its safe haven status

keeps outweighing the negative interest rates that really should've spurred outflows and produce currency weakness.

There is an irony in the fact that one of the reasons behind the Federal Reserve's moderating of its U.S. rate-rise plans last month

was its fear that the rest of the world can't bear far tighter U.S. policy.

And on hearing that, it appears that investors then duly went and bought the rest of the world.

So either markets think that the Fed is overly fearful about the global economy, or, for want of a better idea,

they're happy to stick with the sort of Fed-to-the-rescue theme that's worked so well in investment around the world in recent years.

Neither, however, suggests the kind of confidence the sustained rallies are made of.