How the One-port SAW resonator works??

Hi,All
I want to build a oscillator,in order to get very high Quanlity-factor&very high freqency.
So i decide to use SAW resonator.

The datasheet recommend the circuit below.

I have some idears totally different with the datasheet

I think here in the circuit there is no effect of the SAW.i don't know what role it plays a Capactor,a Inductor or a pure Resistor,in my opinion i think the circuit will oscillate too without the SAW,the frequency is determined by L1,C1,C2,~~~~~,it's a classic Colpitts oscillator~~~~

In order to prove my opinion i simulate the circuit(without SAW)in pspice,it works well~~~~~~~

But the circuit (with SAW) is the one in the datasheet,so i don't think the manufacturer will give us a foolish circuit,

So~~~How the SAW work in this circuit below??

Thanks

My question is:

Why the frequency is determined by SAW only,in spite of C1&C2~~~~