Actions are definitely important in Islam. As Allah reprimands some of the the believers:
O you who have faith! Why do you say what you do not do? It is greatly outrageous to Allah that you should say what you do not do. (61:2-3)
So, it is clear that one has to do good actions to preach. But doing good actions does not substitute preaching. This is based on a lot of evidences:
You are the best nation [ever] brought forth for mankind: you preach what is right and forbid what is wrong, and have faith in Allah. And if the People of the Book had believed, it would have been better for them. Among them [some] are faithful, but most of them are transgressors. (3:110)
They have faith in Allah and the Last Day, and bid what is right and forbid what is wrong, and are active in [performing] good deeds. They are among the righteous. (3:114)
But the faithful, men and women, are comrades of one another: they bid what is right and forbid what is wrong and maintain the prayer, give the zakāt, and obey Allah and His Apostle. It is they to whom Allah will soon grant His mercy. Indeed Allah is all-mighty, all-wise. (9:71)
Allah clearly links righteousness to bidding what is right and forbidding what is wrong (which is verbal preaching) along with actually doing the good actions themselves.
The following hadith is also a representation of this concept:
Messenger of Allah (ﷺ) say: If any one you sees something objectionable, he should change it with his hand if he can change it with his hand. (The narrator Hammad broke the rest of the tradition which was completed by Ibn al-‘Ala’.) But if he cannot (do so), he should do it with his tongue, and if he cannot (do so with) his tongue he should do it in his heart, that being the weakest form of faith. (Sunan Abi Dawud)
Here, the Prophet (SAW) goes even further and states that you have to even physically stop the evil you see and not just verbally preach that it is wrong. Just doing good actions, does not fulfill the obligations as stated.