(CNN) Calling balls and strikes is difficult when you're partially blind.

That's the situation Senate prognosticators are in when it comes to this year's races. In the early going, there just isn't a lot of good polling data out there to understand the playing field.

Democrats need a net gain of two seats to pick up control of the Senate. CNN rates 11 Senate races as either competitive (i.e. leaning towards one party) or as a toss-up, including 3 Republican-held seats and 8 Democratic held seats. Most of these seats have very little non-partisan polling for them.

In the median race, there have been just two non-partisan polls of the expected or actual matchup occurring that have been released publicly since the beginning of the year. Now in some races there have been a ton of non-partisan polls such as Florida (12) or Missouri (7), but in other races there have been zero.

While a number of key Senate races haven't been polled at all this cycle, every single competitive race had at least one poll taken in it by this point in the last midterm cycle in 2014.

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