Yes 100%, No with 100%
Now in your mind the question pop-ups that what is 100%, it means that when teachers were giving their 100% effort for their students while teaching English. Any faculty is important as much students are but if teachers were doing mistakes, or teaching wrong things than it absolutely shows the bad result in the performance of the student in speaking English. But when the teacher is putting their full efforts the results gone 95% perfect for their English speaking fluently.
There are following things which tell the reasons that how English teachers make full efforts:
1- while teaching how she/he giving you the best examples.
2- does faculty is taking responsibility to understand student problem.
3- do they correcting their mistakes and doubts over time and on the spot or not.
4- providing them homework for finding something new every day.
5- long discussion in groups on some interesting topics in English.
6- taking regular surprise tests on the past topics of English.
7- helping in removing the hesitation of speaking in front of anyone.
8- do they giving motivation for the next day, so that student will encourage to attend all the classes of English speaking.
9- does English teacher is able to make the good environment for studies and practice in classrooms.
10- they are able to complete course full structure on time or not.
If they follow these few things then teachers are making their full potential to their kids or students.
As the teacher is important and responsible for few things mentioned above but a student is also that much important to play their role on time like if they are giving some homework, and giving any topic for discussion then the students have also put their energy to take initiative so that both purposes will be solved. A student is only responsible for their results because an English teacher can guide us and tell us about the right thing to do but how students were following that instruction and how much they are putting their own effort to gain benefits from their mentors.
Hence, like we cannot clap form one hand only we need both palms to celebrate for clapping the same thing is also related to a relationship between teachers and their students they are complimentary so dependency of both the parties on each other is needed for perfect results. Yes, teachers effort makes you perfect in English speaking.