Floor standing speakers in entertainment center

It can't hurt to try?  At least they are front ported.  I would make sure that you keep them as far forwards as possible.

Elevick, I measured it and it has about 4-5 inches away from the back. 

You need to soffit mount. This requires a flat front surface and a method to flush mount the baffle of your speaker so that it is seamless. If you don’t flush mount and your cabinetry has holes then you will get plenty of edge diffraction. Also the cabinet need to be inert and heavily braced or yo will get unwanted vibrations. Finally - this setup will boost your bass by 3dB from about 200Hz down - so you may need to adjust for that.

Here is an example

https://dt7v1i9vyp3mf.cloudfront.net/styles/news_large/s3/imagelibrary/q/qa_0116_03.jpg?4CMSefIKMUlI...

It is ideal for bass response (no quarter wave cancellation at all) but it is tricky to do correctly as any coupling of the speaker and the wall can give unwanted vibration...and because the bass is so precise you will excite room modes .

Appreciate shadorne your input, the cabinet is built-in and it looks like it’s heavily braced. Actually I have my sub(golden ear force field 3) behind the tv and it sounds acoustically good. I’m just not getting the sound I wanted on my in-ceiling speakers (B&W ccm663) that’s why I decided to put front speakers and just use the in-ceiling speakers for atmos setup.