Will subcision and suction therapy give a big improvement on these scars? (Photo)

Yes, my preferred PRIMARY method in your case would be cannula subcision with HA buffer, secondary method is with RF microneedling. Saucer scars are notoriously difficult to treat as you would have dermal and subdermal fibrosis. 3-5 sessions then re-evaluate. Acne scar revision is a sub-specialised field. For the best results, one should target the acne scar type with ideal treatments and not just one device. 
For example deep ice pick scars, and narrow box car scars can be treated with TCA CROSS peels, mixed scars, rolling, and atrophic scars treated with fractional devices such as Fraxel, fractional lasers, PRP and INFINI radiofrequency. Atrophic scars (depressions) can be treated with either fat grafts, or dermal fillers. Tethered and anchored scars are best treated with surgical techniques such as subcision. Other surgical techniques that we use include punch elevation, surgical elevation, punch excision and traditional excision of focal scars. 
The majority of patients will have a collection of different scar types, and hence a tailored treatment METHOD will be best. Careful examination, especially under angled lighting with scar mapping will give you an understanding of what are the best options for your scars. In the majority of patients its finding the correct combination that give you best results, and everyone is unique! All the best, 

Dr Davin Lim. Acne scar dermatologist specialist. Brisbane, Australia.